HTH Frequently Asked Questions

HTH™ test strips provide fast, reliable readings suitable for routine pool maintenance and daily monitoring. When used with the HTH™ Test to Swim™ app, results are digitized and translated into clear treatment recommendations.

Yes. The Maintenance Reminders feature lets you set up weekly reminders for pool and spa care tasks — water testing, shock treatments, filter cleaning, and more. Reminders are delivered as push notifications right to your phone.

Yes. Enable Push Notifications in your settings, then turn on Weather Alerts to receive notifications when weather conditions in your area might affect your pool or spa water quality. Make sure your address is up to date in your myHTH® profile for accurate local alerts.

No. You can test your water and receive recommendations without an account. Creating a free myHTH® account adds the ability to save your water test history, track results over time, and keep favorite HTH™ products in one place for easy reordering.

Yes. The free HTH™ Test to Swim™ app (iOS and Android) lets you scan HTH™ test strips with your smartphone camera and instantly receive personalized chemical recommendations and dosage calculations. It connects directly to your pool's volume and current readings, eliminating the guesswork of reading color charts and calculating doses manually.

Yes. The app supports both pool and spa water testing. Scan HTH™ 6-Way Pool Test Strips directly with your phone's camera, or use the in-app interactive color chart with HTH spa™ Test Strips for hot tub and spa results.

HTH™ 3" Chlorine Tabs ULTRA deliver five-in-one treatment: chlorine sanitizer, clarifier, algaecide, stain and scale preventer, and water softener. This comprehensive formula is designed to minimize the number of additional products needed during the swim season.

HTH™ 3" Chlorine Tabs ULTRA significantly reduce the need for separate clarifiers, algaecides, and stain treatments during routine maintenance. However, you will still need to balance pH, alkalinity, and calcium hardness and shock weekly throughout the swim season.

Place HTH™ 3" Chlorine Tabs ULTRA in a chlorine floater, automatic feeder, or skimmer basket—never directly on pool surfaces. Start with 1 tab per 10,000 gallons per week, then adjust the feeder setting to maintain free chlorine between 1–4 ppm. Since HTH™ 3" Chlorine Tabs ULTRA include clarifier, algaecide, and stain control, you may need fewer additional products during normal maintenance.

Each HTH™ 3" Chlorine Tab ULTRA typically dissolves over 5–7 days, depending on water temperature, circulation rate, feeder setting, and how often the pool is used. Higher water temperatures and frequent pool use can cause tabs to dissolve faster. Check your feeder or floater every 3–4 days and replenish it before the tabs fully dissolve to avoid gaps in sanitation.

During routine weekly maintenance, when the pool is already in good chemical balance, HTH™ 3" Chlorine Tabs ULTRA can significantly reduce the need for separate clarifier and algaecide products. However, they are maintenance products—if you have an active algae bloom, severe cloudiness, or a heavily contaminated pool, you will still need a dedicated shock treatment and possibly a targeted algaecide.

Yes. HTH™ 3" Chlorine Tabs ULTRA use trichlor, which contains cyanuric acid (CYA). Using trichlor in a saltwater pool will gradually raise CYA levels. Saltwater pools benefit from CYA levels of 30–50 ppm, and HTH™ 3" Chlorine Tabs ULTRA may help maintain those levels.

HTH™ 3" Chlorine Tabs ADVANCED Wrapped use the same multi-action formula as standard HTH™ 3" Chlorine Tabs ADVANCED, but each tab comes in its own sealed wrap. This helps reduce chlorine dust, lessen chlorine odor in the pail, and limit direct skin contact during handling.

Yes. Remove the wrapper before adding the chlorine tablet to your floater, automatic feeder, or skimmer basket.

Unwrap the tab and add it to a chlorine floater, automatic feeder, or skimmer basket. Use 1 tab per 10,000 gallons per week as a starting point, then adjust as needed to maintain free chlorine between 1–4 ppm.

The wrapped and unwrapped versions of HTH™ 3" Chlorine Tabs ADVANCED contain the same formula and typically dissolve over 5–7 days under normal pool conditions. Test the chlorine level every 3–4 days and replace the tabs as needed.

Individual wrapping minimizes direct chlorine exposure during handling, reducing chlorine dust and skin contact while helping lessen chlorine odor in the pail. Each sealed wrap also protects the tab from humidity, which can cause unwrapped tabs to break down over time.

Yes. HTH™ 3" Chlorine Tabs ADVANCED Wrapped contain the same multi-action formula as standard HTH™ 3" Chlorine Tabs ADVANCED—trichlor sanitizer, built-in clarifier, and algaecide. The only difference is the individually wrapped packaging for easier, cleaner handling. Performance and dosing are the same.

Calcium hypochlorite (cal hypo) tablets contain no cyanuric acid (CYA), unlike standard trichlor tablets. This means they provide strong chlorine sanitation without increasing your pool's stabilizer level, making them ideal when CYA is already at or near 50 ppm.

Switch to cal hypo tablets when your CYA level is above 50 ppm, when standard chlorine tablets are no longer keeping up with demand, or when you want effective sanitation without adding more CYA to the pool water.

To shock with cal hypo, use approximately 1 lb per 10,000 gallons to raise free chlorine by roughly 5–7 ppm. The actual dose varies by product concentration—always read the label. Add the product in the evening with the pump running and retest before entering the pool.

Yes. Cal hypo tablets are compatible with vinyl liner, plaster, fiberglass, and saltwater pools. Always use a cal hypo feeder, floater, or skimmer basket—never place tablets directly on pool surfaces, where they could cause bleaching or damage.

If the pH is above 7.6, HTH™ Brilliance Cal Hypo Chlorine Tablets can temporarily cause slight cloudiness or a fine white residue—this is normal and should clear quickly with circulation. They do not cause foaming. If the pool water remains cloudy, test all chemistry levels first because cloudiness is typically caused by a water balance issue rather than a product reaction.

Both HTH™ Brilliance Cal Hypo Chlorine Tablets and liquid chlorine are stabilizer-free chlorine sources that will not raise CYA. Liquid chlorine acts faster and is easy to pour, but it has a shorter shelf life, requires measuring for accurate dosing, and is less convenient to store. HTH™ Brilliance Cal Hypo Chlorine Tablets dissolve slowly over 5–7 days for ongoing maintenance, making them more suitable for continuous sanitation. Use liquid chlorine for fast boosts and HTH™ Brilliance Cal Hypo Chlorine Tablets for steady maintenance without CYA buildup.

HTH™ Liquid Chlorine is a fast-acting sanitizer used to quickly raise chlorine levels, shock pools, and maintain day-to-day sanitation. It starts working immediately.

Use liquid chlorine when you need a quick chlorine boost, including after heavy rain, after a pool party, at the first sign of algae, or for shock treatments. Tablets are better for slow, steady day-to-day maintenance.

Pour liquid chlorine slowly around the edge of the pool near the return jets, with the pump running, preferably after sunset to reduce chlorine loss from sunlight. Allow 4–6 hours of circulation before retesting chlorine levels.

No. Liquid chlorine does not contain cyanuric acid (CYA), so it will not raise CYA levels. This is an advantage when CYA is already high, but it also means liquid chlorine loses strength quickly in direct sunlight when there is not enough stabilizer in the pool water.

Store HTH™ Liquid Chlorine in a cool, shaded, well-ventilated area away from direct sunlight and heat. High temperatures cause the chlorine to lose strength more quickly and can cause the container to bulge or leak. Keep it in the original sealed container away from other chemicals, especially acids, which can react violently with liquid chlorine. HTH™ Liquid Chlorine has a shelf life of approximately 3–6 months under ideal conditions; check its strength before use.

To shock a pool using liquid chlorine that contains 10–12.5% sodium hypochlorite, use approximately 1 gallon per 10,000 gallons to raise free chlorine by roughly 5–7 ppm. For severe algae or very green pool water, use 2 gallons per 10,000 gallons. Add it in the evening near the return jets with the pump running. Retest after 8 hours of circulation.

HTH™ Chlorine Granules Ultra provide all-in-one treatment with fast-dissolving chlorine sanitizer, algae prevention, water clarification, and stain and scale control. They can be used for regular maintenance or as a shock treatment.

Chlorine granules dissolve rapidly, making them effective for quickly raising chlorine levels or shocking the pool. Tablets dissolve slowly over 5–7 days for steady, ongoing maintenance. Use granules for fast correction and tablets for long-term sanitation.

With the pump running, broadcast the granules evenly across the pool surface, especially over the deep end. Do not add granules to the skimmer. Allow 4–8 hours of circulation, then retest levels before entering the pool.

HTH™ Chlorine Granules Ultra are a cal hypo-based formula and do not contain cyanuric acid (CYA). This means they provide powerful sanitation without raising stabilizer levels, which is especially beneficial when CYA is already elevated.

Yes. HTH™ Chlorine Granules Ultra can be used for weekly maintenance dosing and shock treatments. For maintenance, broadcast a smaller dose to maintain free chlorine between 1–4 ppm. For shocking, use the full shock dose of 1–2 lbs per 10,000 gallons. The multi-action formula—sanitizer, clarifier, algaecide, and stain control—makes it an efficient all-in-one choice for both purposes.

Calculate your pool's volume in gallons using the HTH™ Pool Volume Calculator at hthpools.com. For weekly maintenance, use the dosing chart on the product label based on your pool volume and current chlorine level. For shocking, the standard starting dose is 1 lb per 10,000 gallons for routine treatment or 2 lbs per 10,000 gallons for cloudy pool water or early algae. Never pre-dissolve the granules before adding them.

HTH™ Algae Guard+ Ultra is a concentrated algaecide that prevents and treats green, yellow (mustard), and black algae. It provides up to 30 days of protection with one monthly application and can also help clear an existing algae problem.

Always shock your pool first, wait 24 hours for chlorine levels to return to 1–4 ppm, and then add algaecide. Chlorine levels above 5 ppm can deactivate algaecide before it can work. The correct order is shock, wait, and then add algaecide.

Wait at least 15–30 minutes after adding algaecide and verify that chlorine levels are between 1–4 ppm before entering the pool. Some algaecides may cause temporary foaming—this is normal and will dissipate.

HTH™ Algae Guard+ Ultra provides up to 30 days of protection against green, mustard, and black algae. HTH™ Algae Guard Advanced provides weekly protection against those same three algae types. HTH™ Algae Guard 10 is a weekly preventive designed primarily for green algae in clear, balanced pools.

Although algaecide works best as a preventive treatment, a larger dose can typically treat existing algae. Follow the product directions on the label for treating existing algae.

Absolutely. That is the best time to use it. Applying HTH™ Algae Guard+ Ultra once a month when your pool water is clean and clear can help prevent algae before it appears. Preventing algae is easier and more cost-effective than treating it. A monthly application provides up to 30 days of protection and is especially helpful during heat waves, after heavy rain, or at the start of the swim season.

For visible algae or active growth, apply 2 fl oz of HTH™ Algae Guard+ Ultra per 1,000 gallons of pool water. For prevention before algae appears, apply 1 fl oz per 1,000 gallons and repeat once per month. Test and balance the water first, keep the pump running during application and remember that the exact dose can vary with the algae type and water conditions.

HTH™ Algae Guard Advanced is a weekly-use algaecide that prevents green, yellow (mustard), and black algae from forming in pool water. It is designed for regular maintenance to keep pools algae-free throughout the swim season.

For maintenance, add HTH™ Algae Guard Advanced once a week during the swim season or after every shock treatment. Increase the frequency during hot weather, heavy rain, or periods of heavy pool use, when algae risk is greatest.

Add the recommended weekly dose directly to the pool with the pump running, distributing it around the pool's edge. Chlorine levels above 5 ppm can deactivate algaecide, so wait 24 hours after shocking before adding HTH™ Algae Guard Advanced. For maintenance, apply it once a week throughout the swim season. For a mild algae problem, use it with shock for better algae control.

HTH™ Algae Guard Advanced is formulated to prevent and treat green, yellow (mustard), and black algae. Its higher concentration compared with HTH™ Algae Guard 10 provides broader and longer-lasting protection—especially during hot weather or for pools that have had algae problems in the past.

Yes. HTH™ Algae Guard Advanced is compatible with saltwater, vinyl liner, and all standard pool types. Saltwater pools are not immune to algae, especially when the salt chlorine generator struggles to keep up during heat waves or periods of heavy pool use. Adding algaecide once a week is a smart addition to any saltwater pool maintenance routine.

HTH™ Algae Guard 10 is a weekly preventive designed primarily for green algae in clear, balanced pools. HTH™ Algae Guard Advanced provides weekly protection against green, mustard, and black algae. HTH™ Algae Guard+ Ultra provides up to 30 days of protection against all three algae types and is ideal for pools that need stronger, longer-lasting coverage. Choose the product that best matches your pool maintenance needs.

Use HTH™ Algae Guard 10 as a weekly preventive treatment when your pool is already clear and chemically balanced to help stop green algae before it starts.

HTH™ Algae Guard 10 provides weekly green algae prevention for clear, balanced pools. HTH™ Algae Guard Advanced provides weekly protection against green, mustard, and black algae. HTH™ Algae Guard+ Ultra protects against all three algae types for up to 30 days. Choose the product that best matches your pool maintenance needs.

Chlorine above 5 ppm can deactivate algaecide, so wait 24 hours after shocking and confirm chlorine has returned to 1–4 ppm. Then add the recommended dose of HTH™ Algae Guard 10 to the pool water with the pump running, distributing it around the pool's edge.

Yes. HTH™ Algae Guard 10 is compatible with saltwater, vinyl liner, and all standard pool types. Saltwater pools are not immune to algae—the chlorine generator can struggle during heat waves or periods of heavy pool use. A weekly algaecide treatment is a smart addition to any saltwater pool maintenance routine.

For maintenance, add algaecide once a week during the swim season. Increase the frequency during stretches of hot weather, heavy rain, or periods of heavy pool use—all conditions that stress your chlorine and increase the risk of algae. Consistent weekly dosing is easier and more cost-effective than treating an active algae bloom.

HTH™ Algae Guard 10 is formulated for prevention and light maintenance—it is not strong enough to clear an existing algae bloom on its own. For an existing algae bloom, shock the pool with 2–3 lbs of shock per 10,000 gallons, brush all surfaces, and run the filter continuously. Once chlorine levels return to 1–4 ppm, add algaecide. For severe algae blooms, step up to HTH™ Algae Guard+ Ultra or HTH™ Green to Blue Advanced.

HTH™ Algae Guard 10 has minimal effect on pH when used as directed, though some algaecides may cause temporary foaming. Test pool water before and after use. Chlorine above 5 ppm can deactivate algaecide, so wait for levels to return to normal.

HTH™ Green to Blue Advanced is a two-step treatment system designed to restore a green, algae-filled pool to clear blue water. Step 1 is a cal hypo shock that kills algae. Step 2 is a flocculant that gathers dead algae and debris so they can be vacuumed to waste. When used as directed, the system typically restores water clarity within 24 hours.

Step 1: Add HTH™ Green to Blue Advanced I, a cal hypo shock, directly to the pool with the pump running. Step 2: Move the multiport valve to "recirculate" and add HTH™ Green to Blue Advanced II, a flocculant, to the skimmer. Circulate for one hour, then turn off the pump. The next day, vacuum the sediment to waste. IMPORTANT: YOU MUST HAVE A MULTIPORT VALVE THAT CAN VACUUM TO WASTE TO USE THIS PRODUCT.

Most pools clear within 24 hours when HTH™ Green to Blue Advanced is used as directed. Pools with severe algae blooms may take longer and require a second treatment. Brushing the pool surfaces will help speed up the process.

If the pool is still green after 24 hours, a second dose of HTH™ Green to Blue Advanced I may be needed. After adding it to the pool, wait another day and proceed to vacuum the sediment to waste. You must have a multiport valve that can vacuum to waste to use this product.

Yes. HTH™ Green to Blue Advanced can be used in saltwater pools. Salt chlorine generators often struggle to keep up with the demand of a heavy algae bloom, making a direct shock and flocculant treatment necessary. Follow the standard HTH™ Green to Blue Advanced instructions—the system is compatible with saltwater pool chemistry and will not harm the generator cell.

Before starting HTH™ Green to Blue Advanced, ensure the pH is between 7.2–7.6—high pH significantly reduces the effectiveness of the shock step. The kit includes a cal hypo shock and a strong flocculant. Once the treatment is complete and the pool is clear, resume your normal maintenance routine with weekly chlorine tabs, testing, and algaecide. You may need a second treatment for very severe algae blooms. IMPORTANT: YOU MUST HAVE A MULTIPORT VALVE THAT CAN VACUUM TO WASTE TO USE THIS PRODUCT.

Pool shock is a high-dose chlorine treatment that rapidly raises chlorine to destroy bacteria, algae, chloramines, and organic contaminants. Shocking restores water clarity and sanitizer effectiveness when regular maintenance chlorine is not enough.

Shock your pool at least once a week during peak swim season and always after heavy rain, a large pool party, a visible algae bloom, strong chloramine odor, or when free chlorine drops to zero.

With the pump running, broadcast across the pool evenly. Shock in the evening to prevent sunlight from degrading the chlorine. Wait until free chlorine drops to 1–4 ppm before swimming—usually 8–24 hours.

For routine shock treatment, always read the product label for specific dosing instructions, as concentrations vary by product.

Yes. Pool shock can kill green, mustard, and black algae. Always follow the product label for the correct dose and treatment instructions.

Pool shock is a concentrated chlorine treatment—not the same as the regular maintenance chlorine in tablets or liquid form. Shock delivers a high-dose, fast-acting burst of sanitization, whereas tablets provide a slow, steady baseline chlorine level.

Yes. Chlorine-based shock degrades over time, especially when stored improperly. Keep shock in a cool, dry place away from direct sunlight and moisture. Clumping, discoloration, or a strong odor can indicate degraded product. Properly stored shock has a shelf life of approximately one year.

HTH™ Pool Care Shock is a Cal Hypo pool shock with 52% calcium hypochlorite as the active ingredient. Its CYA-free formula boosts chlorine quickly to help kill bacteria and algae and clear cloudy water without adding cyanuric acid. Use this chlorine shock for pools only as directed, and never mix it with other pool chemicals.

HTH™ Pool Care Shock is a fast-acting, quick-dissolving pool shock treatment once it is broadcast across the pool with the pump running. Add it in the evening, brush away any settled granules and keep swimmers out until testing shows free available chlorine is back within 1–4 ppm. Water conditions affect the timing, so test the water instead of relying on a set number of hours.

No. HTH™ Pool Care Shock is labeled for swimming pool treatment. For a spa or hot tub, use a product formulated for the smaller, hotter water environment, such as HTH spa™ Non-Chlorine Shock Oxidizer. It is compatible with chlorine and bromine spa systems and helps clear cloudy water and odors without raising chlorine levels. Always follow the product label.

HTH Shock Advanced is a multi-action shock that combines fast-acting chlorine with clarifier and algaecide. Unlike basic shock, it simultaneously kills bacteria, destroys algae, and clarifies water in a single treatment.

HTH Shock Advanced is a multi-action cal hypo-based shock that kills bacteria, destroys algae, and clarifies water in a single treatment. Use it for weekly routine shocking, after heavy pool use, after rain, or when water starts looking hazy or starts developing algae. The built-in clarifier means your water clears faster after shocking compared to basic shock.

Shock Advanced is a versatile all-in-one formula combining chlorine, clarifier, and algaecide—ideal for weekly maintenance shocking and mild problem correction. Shock Ultra contains a clarifier, algaecide, stain and scale control, and water softener. Shock Ultra is also ideal for weekly use.

No. HTH Shock Advanced is a calcium hypochlorite (cal hypo) formula and contains no cyanuric acid. This means it delivers a powerful chlorine dose without raising your CYA levels—an important advantage when stabilizer is already at 50 ppm or above. Using cal hypo helps avoid increasing CYA, which may reduce the need to partially drain and refill the pool to lower CYA levels. HTH Shock Advanced is compatible with vinyl-liner, fiberglass, plaster, and saltwater pools.

For routine weekly shocking, use one bag per 13,500 gallons. For cloudy water or early algae, double the dose. Pour slowly around the pool perimeter with the pump running. Shock in the evening to prevent sunlight from degrading the chlorine. Wait until free chlorine returns to 1–4 ppm before swimming.

Yes. HTH Shock Advanced can be used instead of liquid chlorine for weekly treatment. It includes clarifier and algaecide, providing three-in-one protection in a single dose. The premeasured bags also make dosing convenient. Always follow the product label for dosing and application.

Wait until free chlorine levels drop back to 1–4 ppm—typically 8–24 hours after treatment, depending on dose, sunlight, and pool size. Always test with HTH 6-Way Test Strips or a test kit before re-entry. Never swim if chlorine is above 5 ppm. If you shock your pool in the evening and allow it to circulate overnight, it will often be ready by morning.

HTH Shock Ultra is a fast-dissolving, high-concentration formula that provides maximum chlorine impact for severely green, cloudy, or neglected pools. Its rapid dissolution means it starts working faster and allows faster re-entry time after treatment.

HTH Shock Ultra is the brand's multi-functional, fast-dissolving shock formula. It is engineered for maximum chlorine delivery in the shortest time—this product also clarifies, prevents algae, helps minimize stains and scale formation, and softens the water.

All HTH shock products are formulated for rapid dissolution—they begin dispersing within minutes of being added to water. This fast action means the chlorine starts working immediately, which is critical when dealing with a serious algae bloom or contaminated water that needs immediate treatment.

For a severely green pool, balance pH to 7.2–7.6 first because high pH dramatically reduces shock effectiveness. Add 2–3 lbs of Shock Ultra per 16,750 gallons, pre-dissolved in a bucket of water. Run the filter continuously for 24–48 hours, brush all surfaces every 8 hours, then vacuum settled debris. Add algaecide once chlorine drops to 1–4 ppm. A second treatment may be needed for black or mustard algae.

All HTH shock products are formulated to dissolve quickly and start working immediately. HTH Shock Ultra contains additional ingredients that clarify, treat algae, prevent stain and scale formation, and soften the water. For serious algae or contamination problems, the speed of chlorine delivery matters—fast-dissolving shock starts killing bacteria and oxidizing algae sooner, which translates to visibly faster results.

Yes. HTH Shock Ultra is compatible with vinyl-liner, fiberglass, plaster, and saltwater pools. For routine use, Shock Ultra can be added directly to the pool with the pump running. For severe green-pool treatment, pre-dissolve it in a bucket of water as directed on the product label.

For routine shocking, use one bag per 16,750 gallons. For green or cloudy water, double the dose. For severe green or black algae or a fully neglected pool, use triple the standard dose. Always read the label for exact dosing. Test after 24 hours and repeat if the chlorine has been fully consumed while treating the algae.

HTH Salt Shock is specifically formulated for saltwater pools. Even with a salt chlorine generator, your pool can experience chlorine demand spikes from heavy use, algae, or storms—situations where your generator cannot keep up. HTH Salt Shock quickly restores chlorine levels without affecting your salt balance.

Add the recommended dose of HTH Salt Shock to the pool with the pump running, preferably in the evening to prevent sunlight from degrading the chlorine. Broadcast around the pool perimeter. Run the filter for 24 hours, retest chlorine levels, and wait until free chlorine is between 1–4 ppm before swimming.

A salt chlorine generator produces chlorine continuously at a low, steady rate, but it isn't designed to produce enough chlorine quickly after heavy pool use, algae blooms, storms, or periods of high heat. When demand exceeds the generator's output, free chlorine drops and algae or bacteria can take hold. HTH Salt Shock rapidly boosts chlorine without affecting your salt balance.

For routine shocking of a saltwater pool, use 1 bag of HTH Salt Shock per 10,000 gallons. For algae treatment or after a storm, use 2 bags per 10,000 gallons. Always read the product label for concentration-specific dosing. Broadcast around the pool perimeter in the evening with the pump running.

HTH Salt Shock is formulated specifically for saltwater pools and will not raise your salt concentration (NaCl). Regular pool shock products can sometimes contain calcium or other compounds that affect water balance in a saltwater system—HTH Salt Shock is designed to avoid those interactions.

Shock your saltwater pool weekly as routine maintenance and always after heavy rain, heavy pool use, visible algae growth, or when free chlorine drops below 1 ppm despite the generator running. Weekly shocking removes accumulated chloramines and organic waste that the generator cannot oxidize on its own.

The HTH Skimmer Basket Insert fits inside your existing skimmer basket and holds 3–4 chlorine tablets. The insert separates the tablets from debris, making it more convenient and less messy when replacing tablets or cleaning the skimmer basket.

Check your skimmer basket at least weekly to see if you need to add tablets and/or clean out the debris. The insert should last several seasons before it needs to be replaced.

HTH skimmer basket inserts are designed to fit most standard residential pool skimmer baskets. If you have an unusually large or custom skimmer, check dimensions before purchasing. The insert comes with a mount and stainless steel screws to attach to the skimmer basket.

While placing tablets in a skimmer basket is common, it is not the recommended method. Trichlor tablets are highly acidic and can corrode metal components and damage pump seals if the pump turns off while tablets are sitting in concentrated contact with equipment. A floating dispenser or automatic chemical feeder is the safer long-term option.

Indirectly, yes. The insert allows the tablets to dissolve steadily and uniformly, helping to maintain a consistent chlorine level, which will help control algae.

A chlorine floater is a plastic dispenser that floats in your pool and slowly releases chlorine from tablets as water passes through adjustable vents. It provides a simple, hands-free way to maintain steady chlorine levels between 1–4 ppm without a permanent feeder.

Open or close the adjustable vents on the bottom of the floater to increase or decrease the rate of chlorine dissolution. Open vents mean more chlorine; closed vents mean less. Check your chlorine level daily until you've found the correct setting for your pool.

The HTH Chlorine Floater is a plastic dispenser that floats freely in your pool, slowly releasing chlorine as water flows through the mesh screens. There are no adjustments needed; simply add more tablets as needed to maintain 1–4 ppm free chlorine. It provides continuous, hands-free chlorination without a permanent feeder installation.

Yes. Remove or anchor the floater away from swimmers during use, especially in smaller pools. Direct contact with the concentrated chlorine around the floater can cause skin irritation. After swimming, return it to the pool to continue releasing chlorine. Never allow children to handle or play with the floater.

The HTH Chlorine Floater is disposable, and the HTH Brilliance Chlorine Floater uses HTH Brilliance Cal Hypo Tablets or 3" trichlor tablets.

HTH Metal, Stain and Scale Control prevents and treats metal staining and calcium scaling on pool surfaces and equipment. It sequesters dissolved metals like iron and copper so they cannot oxidize and leave stains, and it prevents hard water mineral deposits.

Brown or orange staining usually indicates iron in the water; blue-green stains typically mean copper, often from algaecides or copper pipes. Add HTH Metal, Stain and Scale Control to sequester metals before they oxidize and deposit on surfaces. Also test and balance pH and alkalinity.

Do not shock the pool before treating metal stains—oxidizing metals with high chlorine worsens the staining. With chlorine at normal levels (1–4 ppm), lower pH slightly to 7.0–7.2, then add HTH Metal, Stain and Scale Control per the label dosage. Brush the stained areas thoroughly, run the filter continuously, and vacuum settled particles. Retest and balance chemistry after treatment.

Metal stains typically appear as brownish-orange (iron), blue-green (copper), or black (manganese) patches on pool surfaces and do not brush away easily. Algae stains are usually green, yellow, or black and are slippery or fuzzy to the touch. If a chlorine shock treatment removes the staining, it was likely algae. If staining remains or worsens after shocking, metals are the likely cause.

Common sources of pool metals include copper pipes or fittings corroded by low pH water, well water with naturally high iron content, some algaecide products that use copper as the active ingredient, and heat exchangers on pool heaters. Maintaining pH at 7.2–7.6 prevents acidic water from dissolving metals from equipment, and using HTH Metal, Stain and Scale Control sequesters metals before they can deposit.

Scale forms when calcium hardness is too high (above 400 ppm) combined with high pH and alkalinity. Prevent it by keeping calcium hardness between 200–400 ppm, pH at 7.2–7.6, and alkalinity at 80–120 ppm. Add HTH Metal, Stain and Scale Control monthly as a preventive treatment, especially in areas with hard fill water.

Yes. In addition to treating active metal staining, HTH Metal, Stain and Scale Control can be used as a monthly preventive treatment to sequester dissolved metals and inhibit scale formation before they become visible problems. This is especially recommended for pools filled with hard well water or in areas with high mineral content.

HTH Clarifier is a clarifier that causes fine suspended particles—the ones that make water look dull or hazy—to clump together so they can be captured by your filter. Use it when water looks cloudy but all chemical levels are in the correct range.

Cloudy pool water with balanced chemistry is usually caused by very fine particles that are too small for the filter to catch on their own. Common causes include poor circulation, a dirty or clogged filter, fine algae particles after a treatment, or environmental debris such as pollen and dust.

In these cases, a pool clarifier can help. Clarifiers work by binding tiny particles together, so they become large enough for the filter to capture and remove. Learn more about HTH™ clarifier options here: https://hthpools.com/collections/specialty#PoolClarifiers

When chemistry is balanced but water is still hazy, the culprit is usually very fine suspended particles—pollen, dust, dead algae cells, sunscreen residue—that are too small for your filter to capture. HTH Clarifier Advanced (https://hthpools.com/pool-clarifier) works by causing these micro-particles to clump together into larger clusters that your filter can then remove. It does not change chemistry; it improves physical filtration.

With the pump running, add the recommended dose to the pool water near a return jet for quick distribution. Run the pump continuously for 24–48 hours. Do not backwash or clean the filter for at least 24 hours after adding clarifier—you want the filter to capture the clumped particles. If water does not clear within 48 hours, check filter cleanliness first.

Clarifier causes fine particles to clump together gradually so they are captured by your filter over 24–48 hours—the filter does the work. Flocculant (floc) causes particles to clump into large masses that sink to the pool floor in 8–12 hours, where you vacuum them out manually to waste. Clarifier is easier and works with your filtration system. Flocculant is faster but requires vacuuming to waste.

Yes. HTH Clarifier Advanced is compatible with all pool types, including saltwater, vinyl-liner, and concrete pools. It works by improving particle coagulation regardless of the sanitizing system in use.

Use pool clarifier reactively—when water looks hazy or dull despite balanced chemistry. Some pool owners also add a maintenance dose monthly during peak season. If you find yourself needing clarifier weekly, it may signal a deeper issue: a dirty filter, poor circulation, or water that needs a full rebalance.

HTH™ Clarifier Advanced is a fast-acting pool clarifier that helps tiny suspended particles clump together so the filter can remove them. After adding the correct pool water clarifier dose, run the filter for at least eight hours and vacuum settled debris as needed. Water condition and filter performance affect the timing, so repeat the treatment only as directed if the pool is still cloudy.

Keep swimmers out while adding HTH™ Clarifier Advanced. The product directions do not set a separate fixed wait time, but they do call for at least eight hours of filtration. Before swimming, make sure the water is visibly clear and HTH™ testing confirms free chlorine is 1–4 ppm and pH is 7.2–7.6. If you used pool shock first, wait for the shock's chlorine level to return to range.

For a post-shock clarity treatment, wait 4–12 hours after the shock has circulated before adding HTH™ Clarifier Advanced. Test and balance the water first, dilute the correct dose in a bucket of pool water, then run the filter for at least eight hours. Never mix clarifier and pool shock together or add them at the same time.

Flocculant (floc) works faster than clarifier by causing particles to clump into large masses that sink to the pool floor, where they can be vacuumed out. Clarifier causes particles to clump and be caught by the filter. Use floc when you need rapid clearing—but you must vacuum to waste, not back to the filter.

Add the recommended dose with the pump running for 2 hours to distribute, then turn the pump off and let the pool sit for 8–12 hours (ideally overnight) so debris sinks to the bottom. Vacuum slowly to waste.

HTH Drop Out Flocculant is a flocculant that causes suspended particles to clump into heavy masses that sink to the pool floor within hours. Use it when you need rapid clearing—such as before an event, after a severe algae treatment, or when the pool is extremely cloudy. Unlike clarifier, flocculant requires vacuuming to waste rather than relying on the filter.

First, balance pH to 7.2–7.6. Next, add the recommended dose with the pump running for 2 hours to distribute it. Then turn the pump off and let the pool sit undisturbed for 8–12 hours; overnight is ideal. Vacuum the settled debris very slowly to waste—do not vacuum back to the filter or you will resuspend the particles. Finally, restart the pump and resume normal filtration.

Yes—this is the most critical step. After the particles settle to the bottom, vacuum them directly to waste, bypassing the filter. Vacuuming on the filter setting will recirculate the particles back into the water.

After distributing flocculant and turning off the pump, settled debris should be visible on the pool floor within 4–8 hours. Most pools clear within 8–12 hours. Very cloudy or heavily contaminated pools may need the full 12–24 hours. Resist the urge to turn the pump back on—disturbing the water before vacuuming resuspends all the settled material.

You can, but with an important caution: most above-ground pool filter systems do not have a 'vacuum to waste' option. Without it, you cannot remove the settled debris without sending it back through the filter. If your system lacks a waste bypass, use HTH Pool Clarifier Advanced instead, which works through normal filtration.

Yes—if the sand-filter system has a multi-port valve with Recirculate and Waste or Drain settings. Add HTH™ Drop Out Flocculant as directed, recirculate for two hours, turn the pump off overnight, then vacuum the settled debris directly to waste and backwash the filter. If your pool cannot vacuum to waste, use HTH™ Clarifier Advanced instead.

Wait until the full treatment is complete. HTH™ Drop Out Flocculant needs two hours of circulation followed by overnight settling, direct vacuuming to waste and a filter backwash. Resume normal filtration, then swim only when the water is visibly clear and testing confirms free chlorine is 1–4 ppm and pH is 7.2–7.6. Do not swim while material is settling on the pool floor.

No. HTH™ Drop Out Flocculant binds fine particles, dirt and dead algae so they settle for vacuum-to-waste removal; it does not replace a sanitizer or algaecide for active growth. For severe green water, HTH™ Green to Blue Advanced pairs a Cal Hypo shock that kills algae with a flocculant that drops the dead algae and debris for removal.

HTH Filter Cleaner removes built-up oils, grease, sunscreen, algae, and scale deposits from cartridge, sand, and DE (diatomaceous earth) filters. A clean filter operates at peak efficiency, improving water clarity and reducing the need for additional clarifiers or shock.

For cartridge and D.E. filters, remove the cartridges or grids, rinse with a hose, then soak in diluted HTH Filter Cleaner solution for 8–12 hours or overnight. Rinse thoroughly before reinstalling. For sand filters, add the recommended dose through the skimmer with the pump running, run for several hours, then backwash.

Clean your filter cartridge every 2–4 weeks during swim season with a hose rinse, and deep-clean with HTH Filter Cleaner every 3 months. Backwash sand and DE filters when pressure rises 8–10 psi above the clean starting pressure. Deep chemical cleaning of sand and DE filters should be done at pool opening, closing, and once mid-season.

A clean filter is essential, but cloudiness can persist if the filter media itself is degraded, such as sand older than 5 years or a worn cartridge; there is a channeling issue in a sand filter; water chemistry is still off; or the pump is not running long enough to turn the entire water volume through the filter. Run the pump 8–12 hours daily and verify chemistry is balanced.

Backwashing removes loose debris and some buildup, but oils, sunscreen, algae residue, scale, and chemical precipitates bond to the filter media and cannot be removed by water pressure alone. HTH Filter Cleaner uses a chemical soak to break down these stubborn deposits, restoring the filter's pore structure and flow rate.

HTH Filter Cleaner is suitable for cartridge, sand, and DE (diatomaceous earth) filters. Always follow the specific instructions for each filter type—cartridge and D.E. filters require soaking, while sand filters use a through-system treatment followed by backwashing. Check the product label for filter-specific dilution and application instructions.

Phosphates are nutrients found in fertilizers, leaves, fill water, and swimmer waste that feed algae growth. High phosphate levels (above 200–500 ppb) can make it extremely difficult to control algae, even with adequate chlorine. HTH™ Pool Care Phosphate Remover drops phosphates to near zero, depriving algae of their food source.

The most reliable way to test phosphates is with a phosphate test kit or test strips designed for phosphates. Standard 6-way test strips do not measure phosphates. Signs of high phosphates include chronic algae problems despite adequate chlorine, rapid chlorine consumption, and water that is hard to keep clear. Levels above 200–500 ppb are considered elevated.

HTH™ Pool Care Phosphate Remover uses a lanthanum-based formula that binds to phosphates in the water and causes them to precipitate as a fine white cloud that the filter removes. This process deprives algae of a primary food source, making chlorine more effective at preventing and controlling algae growth.

Add the label-directed dose evenly to the pool with the pump running. The water may temporarily become milky white; this is normal and means the product is working. Run the filter continuously for at least 24 hours, then backwash or clean the filter as directed. Retest after 48 hours and repeat treatment if phosphate levels remain elevated. A compatible pool clarifier can help clear temporary cloudiness more quickly.

Phosphate removal significantly reduces algae’s food supply, making it harder for algae to grow and allowing chlorine to work more efficiently. However, it does not replace algaecide or chlorine; it complements them. In pools with chronic algae issues or very high phosphate levels, removing phosphates can be the missing piece needed to prevent recurring algae problems.

Phosphates enter pool water from many sources: fertilizer runoff, windblown grass clippings, leaves and organic debris, swimmer waste such as sweat and urine, some pool chemicals and algaecides, tap water in some municipalities, and rainwater. Pools near gardens, lawns, or heavily landscaped areas tend to accumulate phosphates fastest.

HTH™ Pool Care Clear Defense is a preventive pool treatment that works continuously to inhibit algae growth by reducing phosphates while helping maintain water clarity. Unlike algaecides that target existing algae, Clear Defense is formulated for weekly use to help prevent algae before it starts.

HTH™ Pool Care Clear Defense is a weekly preventive treatment that reduces algae food, including phosphates. This multifunctional product also contains clarifiers and enzymes that improve water clarity and minimize waterline buildup.

HTH™ Algae Guard products are concentrated algaecides with active ingredients that target algae directly. HTH™ Pool Care Clear Defense is a broader preventive product that inhibits algae growth while supporting water clarity. Think of Clear Defense as a maintenance shield and Algae Guard products as targeted treatment when algae has been identified.

Apply HTH™ Pool Care Clear Defense weekly as part of regular maintenance, after testing the water and once chlorine has returned to 1–4 ppm following shock treatment. For best results, use HTH Clear Defense weekly. Sporadic dosing provides little benefit.

No. HTH™ Pool Care Clear Defense is an algae inhibitor and clarity treatment; it does not replace the oxidation provided by shock. Shock destroys bacteria, chloramines, and organic waste that Clear Defense cannot address. Use both as part of a complete weekly routine: shock first, then add Clear Defense once chlorine returns to 1–4 ppm.

Yes. HTH™ Pool Care Clear Defense is compatible with all sanitizing systems and pool types, including chlorine, saltwater, and vinyl-lined pools. It will not affect water balance when used at the label-directed weekly dose.

HTH™ Pool Care Liquid Solar Blanket forms an invisible barrier on the water surface that reduces evaporation by up to 40%. This helps retain heat and can reduce water, chemical, and energy costs without the hassle of a physical cover.

HTH™ Pool Care Liquid Solar Blanket forms an invisible barrier on the pool water surface that slows the rate at which water molecules escape into the air. This can reduce evaporation by up to 40%, so you refill less often, lose fewer chemicals, and retain more heat.

Shake well, then add the label-directed dose to the pool water surface opposite the skimmer while the pump is running. Reapply weekly for best results. Wait 15 minutes after application before swimming. When used as directed, the product will not affect water chemistry.

A liquid solar blanket is not as effective as a physical cover for heat retention in very cold weather, but it is more convenient and still provides meaningful evaporation reduction throughout the swim season. It is ideal for pool owners who find physical covers difficult to manage or want continuous protection without covering and uncovering the pool daily.

No. When used as directed, HTH™ Pool Care Liquid Solar Blanket will not affect pH, chlorine, alkalinity, or other water chemistry parameters. Its nontoxic formula disperses quickly and does not affect water feel, clarity, taste, or odor. Wait 15 minutes after application before swimming.

By reducing evaporation by up to 40%, a liquid solar blanket can meaningfully reduce water, chemical, and heating costs throughout the swim season. Every gallon that evaporates carries heat and dissolved chemicals with it, so less evaporation means less refilling, fewer chemical top-ups, and lower heating costs, particularly for heated pools.

HTH™ Pool Care Hydra Nourish softens and conditions pool and spa water for a silky, more comfortable swim or soak. It contains aloe vera, hyaluronic acid, conditioning agents, and fragrance to leave water feeling softer and smelling fresh.

HTH™ Pool Care Hydra Nourish softens and conditions pool and spa water to create a more comfortable, silky experience. It reduces the harsh feel sometimes associated with heavily chlorinated or unbalanced water and adds a fresh fragrance that lasts for days.

Add HTH™ Pool Care Hydra Nourish weekly or after each water treatment, following the label directions, to maintain silky-soft water and a fresh fragrance. Do not premix it with other chemicals. When used as directed, it will not significantly affect pH, chlorine, or alkalinity.

HTH™ Pool Care Hydra Nourish is formulated with aloe vera, hyaluronic acid, and conditioning agents to leave water feeling softer and reduce dry-skin sensations. It does not replace proper water balance; maintaining the correct pH remains essential for swimmer comfort. Always use the product as directed and avoid direct contact with skin or eyes.

Yes. HTH™ Pool Care Hydra Nourish is compatible with all pool and spa sanitizer systems and surfaces, including saltwater and vinyl-lined pools. It complements the naturally soft feel that many saltwater pool owners enjoy and can further enhance swimmer comfort.

Water conditioner can help reduce the harsh feel of pool water, but eye irritation is usually caused by poor water balance or chloramines—not chlorine itself. If swimmers experience irritation, test and correct pH, verify free chlorine, and shock as needed to remove chloramines. Once the water is properly balanced, HTH™ Pool Care Hydra Nourish can be added for ongoing comfort.

HTH™ Pool Care D.E. Filter Aid is a powder made from the fossilized remains of microscopic aquatic organisms called diatoms. Added to a D.E. filter after every backwash, it forms a porous coating on the filter grids that traps extremely fine particles and restores filtration efficiency. You will also need to add fresh D.E. powder when starting the filter and after any complete filter cleaning.

After backwashing a D.E. filter, the old D.E. coating is washed away and must be replaced. With the pump running, mix the label-directed amount of HTH™ Pool Care D.E. Filter Aid with water to form a slurry, then pour it slowly through the skimmer nearest the filter. The pump will draw the slurry into the filter and coat the grids. Refer to the filter manufacturer’s manual for the exact amount required for the filter’s surface area.

Adding a small amount of D.E. powder to a sand filter is sometimes used to improve fine-particle filtration. Add only the amount permitted by the filter manufacturer through the skimmer with the pump running. The D.E. can coat the sand and temporarily improve its ability to trap finer particles. Backwash when filter pressure rises.

Add HTH™ Pool Care D.E. Filter Aid after every backwash because backwashing removes the old D.E. coating along with trapped debris. Add fresh D.E. powder when starting the filter and after any complete filter cleaning. For sand filters supplemented with D.E. powder, add a small maintenance dose only as permitted by the filter manufacturer.

When used correctly, HTH™ Pool Care D.E. Filter Aid remains inside the filter and does not enter the pool during normal operation. If a filter grid cracks or a seal fails, D.E. powder may return to the pool and appear as white powder on the pool floor. Inspect filter grids regularly and replace damaged components. Always follow the product label and filter manufacturer’s guidance.

HTH™ Pool Care Kit is an all-in-one seasonal bundle designed to help open or close a pool. It includes two 1 lb bags of HTH™ Pool Care Shock Ultra, one 12 oz bag of HTH™ Pool Care Algae Guard Granules, one 1.25 lb bag of HTH™ Pool Care Metal, Stain & Scale Control, and 10 HTH™ Pool Care 6-Way Test Strips. Each kit treats up to 20,000 gallons.

HTH™ Pool Care Kit is designed for first-time pool owners or anyone who wants a simplified, premeasured approach to seasonal opening and closing. Instead of buying shock, algaecide, Metal, Stain & Scale Control, and test strips separately, the kit bundles complementary products with directions for how and when to use them.

Follow the included directions and every product label. Remove the cover, restore the water level, reconnect the equipment, and circulate the water for at least 8 hours. Test and balance total alkalinity, pH, and calcium hardness. Add Algae Guard Granules through the skimmer, add Metal, Stain & Scale Control to the deepest part of the pool, then add Shock Ultra according to its label. Resume normal sanitizer use and maintain free chlorine at 1–4 ppm. Add products separately, never mix them, and allow each to dissolve before adding the next.

Yes. The kit covers shock treatment, algae control, metal, stain and scale control, and water testing. You will still need an ongoing sanitizer such as chlorine tablets or granules, plus pH adjusters, alkalinity increaser, calcium hardness increaser, or stabilizer when test results indicate they are needed. Think of the kit as a seasonal foundation, not a complete year-round maintenance program.

Yes. HTH™ Pool Care Kit is compatible with both chlorine and saltwater systems and treats up to 20,000 gallons. Saltwater pools still require routine salt-level testing, cyanuric acid management, and salt-cell maintenance. Follow the directions and safety precautions on each included product.

HTH spa™ Test Strips measure total bromine or free chlorine, pH, total alkalinity, and total hardness—the essential parameters used to keep hot tub water clean, comfortable, and balanced.

Test hot tub water at least 2–3 times per week and always before and after heavy use. Hot tubs have a small water volume and high temperatures that cause chemistry to shift quickly, so frequent testing is essential.

Dip the test strip into the water for 2 seconds, remove it, shake it once, then immediately compare each color pad with the chart on the bottle from left to right. Compare the colors in natural or bright indoor light. The reviewed target ranges are bromine 2–4 ppm or chlorine 1–3 ppm, pH 7.2–7.8, total alkalinity 80–120 ppm, and calcium hardness 150–200 ppm.

Pool and spa test strips measure similar parameters but are calibrated for different ranges. Spa strips account for smaller water volume, higher temperature, and hot-tub target ranges—for example, bromine rather than chlorine and a slightly broader acceptable pH range. Always use spa-specific strips for hot tubs.

Compare each color pad with the chart on the bottle. For any parameter outside the target range, adjust total alkalinity first, then pH, calcium hardness, and sanitizer. Make one adjustment at a time, circulate the water for the label-directed period, and retest before making the next correction. The reviewed target ranges are alkalinity 80–120 ppm, pH 7.2–7.8, calcium hardness 150–200 ppm, bromine 2–4 ppm, and chlorine 1–3 ppm.

Hot tub chemistry is highly dynamic. Small water volume, high temperature, and jet aeration cause rapid changes. A single soak can noticeably change sanitizer and pH levels; this is normal. Testing 2–3 times per week and always before use is the best way to catch imbalances before they affect bathers or equipment.

HTH spa™ Alkalinity Up raises total alkalinity in hot tub water to the recommended range of 80–120 ppm, creating a stable buffer that prevents pH from fluctuating. Stable alkalinity helps protect equipment, surfaces, and bathers.

Hot tubs experience faster water-chemistry changes than pools because of their small water volume, high temperature, and jet aeration. Aeration causes carbon dioxide to leave the water, which can raise pH and affect alkalinity. As a result, hot tub alkalinity requires more frequent testing and adjustment—at least 2–3 times per week.

With the circulation system running, add the label-directed amount of HTH spa™ Alkalinity Up directly to the water. Allow the water to circulate for 1–3 hours, then retest. Repeat if needed until total alkalinity reaches 80–120 ppm. Add the product gradually; it is easier to add more than to lower alkalinity if you add too much.

Low alkalinity can cause pH to swing unpredictably, sometimes moving several points in a single day. This makes pH difficult to stabilize and can lead to reduced sanitizer effectiveness, skin and eye irritation, corrosion of equipment, and an uncomfortable soaking experience.

Maintain hot tub total alkalinity between 80 and 120 ppm, the same target range commonly used for swimming pools. However, since hot tubs can lose alkalinity faster because of heat and jet aeration, you may need to test and adjust more frequently.

Yes. Raising alkalinity with sodium bicarbonate, the active ingredient in many alkalinity increasers, can raise pH slightly. Make adjustments in small increments and retest between doses. If pH is already at the top of the target range, raise alkalinity gradually and monitor pH closely.

Use the label dosing table to measure HTH spa™ pH Up based on the current pH and the hot tub’s water volume. With the circulation system running, add the measured amount directly into the spa filter skimmer. Circulate for 30 minutes, retest, and repeat if needed until pH reaches 7.2–7.8.

Maintain hot tub pH between 7.2 and 7.8. This range keeps water comfortable for bathers, helps bromine and chlorine sanitizers work effectively, and protects jets, heaters, and seals from corrosion at low pH or scaling at high pH. Water outside this range can damage equipment and cause swimmer discomfort.

If pH keeps dropping after you add pH Up, the root cause is often low total alkalinity. Alkalinity acts as a pH buffer; without adequate alkalinity of 80–120 ppm, pH cannot remain stable. Correct alkalinity first, then address pH. Once alkalinity is in range, pH should require less frequent adjustment.

With the circulation system running, add the label-directed amount of HTH spa™ pH Up directly into the spa filter skimmer. Circulate for 30 minutes, then retest. Repeat in small increments until pH reaches 7.2–7.8; hot tub water responds quickly, so it is easy to overshoot the target.

HTH spa™ pH Up begins working as it circulates and should be retested after 30 minutes. Always complete the full circulation period before adding more. Hot tubs have a small water volume, so changes happen quickly; retesting between doses helps prevent overshooting.

Yes. Sustained low pH below 7.2 makes water corrosive; it can attack acrylic shells, degrade rubber seals and gaskets, corrode metal fittings, damage the heater element, and shorten the life of jets. It can also cause skin and eye irritation. Correcting low pH promptly is one of the most important things you can do to protect your hot tub.

Use the label dosing table to measure HTH spa™ pH Down based on the current pH and the hot tub’s water volume. With the circulation system running, add the measured amount directly into the spa filter skimmer. Circulate for 30 minutes, retest, and repeat if needed until pH returns to 7.2–7.8.

The ideal pH range for a hot tub is 7.2–7.8. pH below 7.2 can cause corrosion and irritation; pH above 7.8 can cause scaling and reduce sanitizer effectiveness.

Hot tub pH tends to rise because jet aeration releases dissolved carbon dioxide (CO?) from the water into the air. As CO? leaves the water, pH can climb. This is normal in hot tubs. Add HTH spa™ pH Down in small increments according to the label, retesting until pH returns to 7.2–7.8.

Use the label dosing table to determine the correct amount of HTH spa™ pH Down for the hot tub’s water volume and current pH. With the circulation system running, add the measured amount directly into the spa filter skimmer. Circulate for 30 minutes, then retest before adding more. Do not mix it with other chemicals.

High pH above 7.8 reduces bromine and chlorine effectiveness, allowing bacteria to survive even when sanitizer is present. It can also cause calcium to precipitate as scale on surfaces, jets, and the heater—one of the most common causes of costly hot tub repairs. Cloudy water and skin irritation are also symptoms of high pH.

Yes. Sodium bisulfate, the principal ingredient in HTH spa™ pH Down, lowers both pH and total alkalinity. If alkalinity is already at the lower end of the 80–120 ppm range, add pH Down in small doses and retest frequently. Dropping alkalinity below 80 ppm can cause pH instability—the opposite of what you want.

Check hot tub pH at least 2–3 times per week and adjust it as test results require. Heavy use, new water fills, and chemical additions can all shift pH. Maintaining total alkalinity at 80–120 ppm can significantly reduce how often pH needs correction.

HTH™ alkalinity increaser raises total alkalinity in pool water to the ideal range of 80–120 ppm, helping stabilize pH so it stops fluctuating. Balanced alkalinity protects pool surfaces, equipment, and swimmers from the effects of corrosive water.

Add HTH™ alkalinity increaser when your total alkalinity tests below 80 ppm. Low alkalinity causes pH to fluctuate erratically, which can lead to chlorine loss, skin irritation, and damage to pool surfaces and equipment.

Unstable pH is almost always caused by low total alkalinity. Alkalinity acts as a buffer that holds pH steady — when it is too low, even small amounts of rain, swimmers, or chemicals can push pH up or down quickly. Raise alkalinity first, then adjust pH.

The ideal total alkalinity range is 80–120 ppm for most pools. Staying within this range helps keep pH stable, allows chlorine to work efficiently, and helps prevent corrosion or scaling on pool surfaces.

With the pump running, add the recommended amount of HTH™ pool alkalinity increaser directly into the pool. Retest after 6–8 hours of circulation and repeat if needed until alkalinity reaches 80–120 ppm.

Yes. HTH™ Alkalinity Increaser is compatible with all pool types including saltwater, vinyl-liner, and concrete pools. Salt chlorine generators still require balanced alkalinity to function properly.

Low alkalinity (below 80 ppm) leads to rapid pH swings, corrosion of metal equipment and pool surfaces, eye and skin irritation, and faster chlorine consumption. Test and correct alkalinity before adjusting pH or adding other chemicals.

High alkalinity (above 120 ppm) can cause pH to rise and resist correction, leading to cloudy water, scaling on surfaces and equipment, and reduced chlorine efficiency. If alkalinity is above 120 ppm, use HTH™ pool pH Decreaser to bring it back into range.

HTH™ Calcium Hardness Increaser raises calcium levels in pool water to the recommended range of 200–400 ppm. Proper calcium hardness prevents water from becoming corrosive, which can etch plaster, and wear down equipment.

When calcium hardness drops below 200 ppm, 'soft' water aggressively pulls calcium from pool plaster, causing etching, pitting, and damage over time.

Most pools should maintain calcium hardness between 200–400 ppm. Plaster or concrete pools perform best at the higher end (250–350 ppm), while vinyl and fiberglass pools can be maintained toward the lower end of the range.

Slowly, add the recommended amout of HTH™ pool calcium hardness increaser directly into the pool with the pump running. Allow 48 hours of circulation before retesting. Never add more than 10 lbs per 10,000 gallons at one time.

Yes. HTH™ Calcium Hardness Increaser is safe for all pool types including vinyl-liner, fiberglass, and saltwater pools. Maintaining proper calcium levels protects every pool type from the effects of corrosive, unbalanced water.

Use HTH™'s 6-Way Test Kit or 6-Way Test Strips to measure calcium hardness. Test your pool water at least once a month, or more frequently at the start of the season or after significant water addition.

HTH™ Chlorine Stabilizer contains cyanuric acid (CYA), which acts like sunscreen for chlorine. Without it, UV rays from sunlight can destroy up to 90% of your pool's free chlorine within two hours, making it nearly impossible to maintain safe sanitizer levels.

For outdoor pools using trichlor or dichlor tablets, maintain CYA between 30–50 ppm. Salt chlorine generator pools typically need 60–80 ppm. Levels above 100 ppm can reduce chlorine effectiveness and are lowered by partially draining the pool.

Rapid chlorine loss in outdoor pools is almost always caused by low stabilizer (CYA) levels. Without enough CYA, direct sunlight destroys chlorine within hours. Test stabilizer levels and add HTH™ Chlorine Stabilizer if CYA is below 30 ppm.

Always check the back of HTH™ Pool Care Chlorine Stabilizer to determine the right dosage for your pool and use hthpools.com/pages/pool-calculator. Add the calculated dose directly through the skimmer with the pump running. CYA dissolves slowly — run the pump for 24–48 hours before retesting levels.

Cyanuric acid is mildly acidic and may slightly lower pH and alkalinity when added in large doses. Always retest pH and alkalinity after adding stabilizer and make any necessary adjustments.

High CYA (above 100 ppm) reduces the effectiveness of chlorine — a condition sometimes called 'chlorine lock' — meaning the pool requires much more chlorine to stay sanitary. The only reliable way to lower CYA is to partially drain and refill the pool.

HTH™ pH Increaser raises low pH back into the ideal range of 7.2–7.6. Low pH makes pool water acidic, which can corrode metal equipment, damage surfaces, irritate swimmers' eyes and skin, and cause chlorine to burn off faster.

The ideal pool pH range is 7.2–7.6. At this level, chlorine works most efficiently, water is comfortable for swimmers, and pool surfaces and equipment are protected from corrosion.

Pool pH can drop due to heavy rainfall, acidic fill water, high bather load, CO2 dissolved from the air, or the addition of certain chemicals like shock or chlorine products. If alkalinity is also low, pH will be especially difficult to stabilize.

With the pump running, add the recommended amount directly into the pool. Run the pump for 4–6 hours before retesting. Adjust in small increments to avoid overshooting the target range (7.2-7.6).

HTH™ pH increaser starts dissolving and acting within minutes of being added. You should retest after 4–6 hours of pump circulation to get an accurate reading and determine if a second dose is needed.

No — add one chemical at a time and wait at least 4–6 hours between additions. Adding pH increaser and chlorine simultaneously can cause localized reactions and makes it impossible to accurately assess the effect of each adjustment. Always adjust pH and alkalinity first, allow them to circulate fully, then add sanitizer last.

HTH™ pH Decreaser lowers high pH back into the safe range of 7.2–7.6. High pH reduces chlorine effectiveness, can cause cloudy water, scaling on surfaces and equipment, and eye irritation for swimmers.

Pool pH commonly rises due to the addition of alkalinity or calcium chemicals, high-pH fill water, saltwater systems, algae growth, or heavy aeration from waterfalls or fountains. If alkalinity is also high, it will push pH up consistently.

With the pump running, broadcast the recommended dose of HTH™ pH decreaser around the deep end of the pool. Never pre-dissolve pH down in a plastic bucket — add it directly to pool water. Retest after 4–6 hours of circulation and adjust if necessary.

High pH (above 7.8) significantly reduces chlorine efficiency, meaning bacteria and algae can survive even with adequate chlorine levels present. It also causes calcium scaling on pool walls, filters, and equipment.

Yes. pH Decreaser (sodium bisulfate or muriatic acid) lowers both pH and total alkalinity. If alkalinity is already in range, use smaller doses and retest frequently to avoid dropping alkalinity below 80 ppm.

Wait at least 4–6 hours after shocking before adding HTH™ pH Decreaser, and vice versa. Adding acid immediately after a high-chlorine shock can cause off-gassing and interfere with both treatments. Always test pH after a shock treatment has distributed fully before making any pH adjustment.

The HTH™ 6-Way Test Kit tests for free chlorine, total chlorine, bromine, pH, total alkalinity, calcium hardness, and cyanuric acid (stabilizer). These are the six most important parameters for maintaining safe, clear, and balanced pool water.

Test your pool water at least 2–3 times per week during swim season. Test more frequently after heavy rain, a large number of swimmers, adding chemicals, or at pool opening and closing. Regular testing prevents problems before they become costly.

Target these ranges: Free Chlorine 1–4 ppm, pH 7.2–7.6, Total Alkalinity 80–120 ppm, Calcium Hardness 200–400 ppm, and Cyanuric Acid 30–50 ppm. Keeping all parameters in range ensures sanitizer effectiveness and swimmer comfort.

Fill the test vial to the indicated line with pool water, add the appropriate reagent drops for each test, cap and invert to mix, then compare the color to the chart on the kit. Test away from direct sunlight for the most accurate color reading.

Yes, this test kit is compatible with both chlorine-based and saltwater pools. Note that it does not test salt (NaCl) concentration — use a dedicated salt test strip or meter if you need to verify salt levels in a saltwater pool.

Compare your results to the ideal ranges. If chlorine is low, add sanitizer or shock. If pH is off, add pH Up or pH Down. For low alkalinity, add Alkalinity Increaser. For low calcium hardness, add Calcium Hardness Increaser. For low CYA, add Chlorine Stabilizer.

HTH™ Pool Care pH Up

HTH™ Pool Care pH Down

HTH™ Pool Care Chlorine Stabilizer

HTH™ Pool Care Shock Advanced

HTH™ Pool Care Alkalinity Up

HTH™ Pool Care Calcium Up

Always adjust chemicals one at a time, starting with alkalinity, then pH, then calcium hardness, then chlorine/stabilizer. Wait 4–6 hours between adjustments and retest before adding the next chemical to avoid overcorrecting.

HTH™ 6?Way Test Strips measure free chlorine, bromine, pH, total alkalinity, calcium hardness, and cyanuric acid (CYA) — the six key parameters needed to maintain balanced, safe pool water.

For added convenience, users can scan their results with the HTH™ Test to Swim app, which analyzes the strip and recommends the exact HTH™ products and dosages needed.

Dip one strip into pool water at elbow depth for 2 seconds, remove without shaking, and hold flat (do not wipe). After 30 seconds, compare the color pads to the chart on the bottle in natural light. Record results and adjust chemicals as needed.

For instant digital results, users can download the HTH™ Test to Swim app and scan the test strip with their phone, or reference the online HTH™ pool test strip color chart at https://HTH™pools.com/pages/pool-test-strip-color-chart

HTH™ test strips provide fast, reliable readings suitable for routine pool maintenance and daily monitoring. When used with the HTH™ Test to Swim app, results are digitized and translated into clear treatment recommendations.

For the most precise measurements — especially at pool opening, closing, or when troubleshooting a problem — the HTH™ 6?Way Liquid Test Kit offers greater accuracy.

After dipping the strip for 2 seconds and waiting 30 seconds, compare each color pad to the matching row on the bottle chart in natural light. Retest if results seem unexpected, as sunscreen, lotions, or cross?contamination can affect readings.

Alternatively, scanning the strip with the HTH™ Test to Swim app eliminates guesswork and automatically interprets the results for you.

Low chlorine readings after dosing can indicate that CYA (stabilizer) is too low, sunlight is consuming chlorine rapidly, the pool has high chlorine demand from algae or organic load, or the strip has expired.

Use the HTH™ Test to Swim app to confirm stabilizer levels and receive specific dosing instructions. Always check the strip expiration date printed on the bottle.

Keep the bottle tightly capped at all times — even brief exposure to humidity degrades the reagent pads. Store in a cool, dry location away from heat, sunlight, and moisture. Never store in a bathroom, near the pool, or in a hot car.

Check the expiration date printed on the bottom of the bottle. When stored correctly, strips typically last 12–18 months after opening.

HTH™ 1-inch chlorine tablets are designed for smaller pools and above-ground pools. They dissolve slowly to maintain a steady chlorine level of 1–4 ppm, continuously killing bacteria and preventing algae.

A general starting point is 1–2 tablets per 5,000 gallons of water per week. Always test chlorine levels after a few days and adjust the number of tablets in your feeder or floater to maintain 1–4 ppm.

Always place chlorine tablets in a floating chlorine dispenser, an automatic chemical feeder, or a skimmer basket — never directly on the pool floor or walls. Direct contact with surfaces can cause bleaching or damage to liners and finishes.

1-inch tablets are sized for smaller pools, feeders designed for 1-inch tabs, and above-ground pools. 3-inch tablets dissolve more slowly and are ideal for larger in-ground pools. Use the size that matches your feeder type and pool volume.

Each 1-inch tablet typically lasts 5–7 days, depending on water temperature, sunlight exposure, pool size, and bather load. Higher temperatures and heavy use will cause tablets to dissolve faster.

No. Trichlor tablets — including 1-inch and 3-inch — should not be used in hot tubs. Their highly acidic pH (~2.8) damages acrylic shells, degrades rubber seals, and rapidly builds up CYA in the small water volume of a spa. For hot tub sanitation, use HTH spa™ Bromine Tablets, HTH spa™ Clear Chlorinating Sanitizer, or other products specifically formulated and labeled for spa use.

HTH™ 3-inch chlorine tablets provide long-lasting sanitation for in-ground and larger pools. Each tablet dissolves slowly over 5–7 days to continuously kill bacteria and prevent algae while maintaining chlorine levels of 1–4 ppm.

Start with 1 tablet per 10,000 gallons of water per week. Adjust up or down based on test results — your goal is to maintain a free chlorine level of 1–4 ppm. Hot weather, heavy use, and high bather loads may require additional tablets.

Low chlorine despite using tablets often means your CYA (stabilizer) is too low and sunlight is destroying chlorine, the pool has a heavy organic load requiring a shock treatment, or your feeder rate needs to be increased. Test all parameters and shock the pool if needed.

Yes. Standard HTH™ 3-inch Chlorine Tablets use trichlor (trichloroisocyanuric acid), which contains approximately 57% cyanuric acid by weight. This means CYA gradually accumulates in your pool as you use them. Test CYA monthly — when it reaches 50 ppm, consider switching to HTH™ Brilliance Cal Hypo Tablets (no CYA) to avoid over-stabilization.

Yes, when used correctly. Never place HTH™ 3" chlorine tablets tablets directly on a vinyl liner — always use a floater or automatic feeder. Trichlor tablets have a very low pH (~2.8) and can bleach or damage vinyl if concentrated contact is prolonged. A floating dispenser distributes chlorine safely throughout the pool without localized surface exposure.

Typically, is it not safe to break chlorine tablets. A better approach for smaller pools is to use HTH™ 1-inch chlorine tablets, which are specifically sized for smaller volumes and allow more precise dosing.

HTH™ 3" Chlorine Tabs ADVANCED combine a slow-release chlorine sanitizer with a built-in clarifier and algaecide. This all-in-one formula helps keep pool water clearer and prevent algae growth while reducing the need for separate products compared with standard chlorine tabs.

During normal maintenance, HTH™ 3" Chlorine Tabs ADVANCED can reduce the need for separate algaecide and clarifier products. They help prevent algae growth and cloudy pool water, but active algae or severe cloudiness may still require targeted treatment.

If your pool water was already out of balance when you switched to HTH™ 3" Chlorine Tabs ADVANCED, the tabs alone may not correct an existing problem—they are designed for maintenance, not remediation. Shock the pool, verify that all chemical levels are in range, and then resume tab use.

Yes. HTH™ 3" Chlorine Tabs ADVANCED use trichlor and contain cyanuric acid (CYA), just like standard 3" chlorine tabs. CYA can accumulate over the season with regular use. Test CYA monthly—when it approaches 50 ppm, consider switching to HTH™ Brilliance Cal Hypo Chlorine Tablets for ongoing sanitation without adding more stabilizer. The clarifier and algaecide in HTH™ 3" Chlorine Tabs ADVANCED are not affected by switching to cal hypo.

HTH™ 3" Chlorine Tabs ADVANCED contain a built-in water clarifier that helps fine suspended particles clump together as each tab dissolves. Rather than waiting for cloudiness to develop before adding a separate clarifier treatment, HTH™ 3" Chlorine Tabs ADVANCED work proactively with a continuous low-dose clarifier. This helps keep pool water clearer between weekly maintenance steps.

Yes. The built-in algaecide in HTH™ 3" Chlorine Tabs ADVANCED makes them a smart choice for pools prone to algae, especially during hot weather or when phosphate levels are high. The continuous low-level algaecide acts as a preventive barrier, making it harder for algae spores to take hold between shock treatments.

The HTH™ Test to Swim™ app uses AI technology to read test strip colors with greater precision than reading by eye in most lighting conditions. For the most accurate scan, take the photo in good natural light and follow the in-app camera guide.

All dimensions are measured in feet. When entering pool or spa dimensions into the app, use numbers and decimals only. For example, if your pool is 8½ feet deep, enter 8.5 in the Depth field. Accurate dimensions ensure the most precise product and dosing recommendations.

After dipping the strip for 2 seconds and waiting 30 seconds, compare each color pad to the matching row on the bottle chart simultaneously. Read chlorine pads in bright, natural light. Retest if results seem unexpected, since sunscreen, lotions, or cross-contamination can affect readings. Scanning the strip with the HTH™ Test to Swim™ app eliminates guesswork and automatically interprets the results for you.

Yes. The app's Universal Water Testing feature lets you manually enter chemical test values from any test strip or test kit and receive personalized treatment recommendations. The app's HTH™ product recommendations work whatever testing method you prefer.

From the app, tap myHTH in the lower right corner to access your account information. From hthpools.com, click the myHTH logo in the upper right corner (desktop) or the menu dropdown (mobile). Click Edit next to General Information, make your changes, and tap Update User Info to save.

Yes. The HTH™ Test to Swim™ app is free to download on iOS and Android, with no subscription required to scan strips, get recommendations, or save your test history.

HTH™ 6-Way Test Strips measure free chlorine, bromine, pH, total alkalinity, calcium hardness, and cyanuric acid (CYA) — the six key parameters needed to maintain balanced, safe pool water. When you scan a strip with the HTH™ Test to Swim™ app, it analyzes each pad and recommends the exact HTH™ products and dosages your water needs.

On the Welcome screen, tap Forgot Password. You'll receive an email with a temporary code and instructions for accessing your account.