How to Remove and Prevent Hot Tub Stains from Your Spa

Woman with a cup in her hand in a hot tub next to a man

A hot tub is synonymous with relaxation and leisure, offering a personal escape into a world of warmth and tranquility. However, hot tub stains can disrupt this serene experience, turning a tranquil spa experience into a visual disturbance. Whether it’s the hot tub yellow stain that appeared overnight or the subtle discoloration you've been ignoring, knowing how to remove hot tub stains is crucial for every spa enthusiast!

You’ve probably been there, staring at an unsightly mark, pondering hot tub stain removal, missing the pristine waters you had previously. Mastering how to remove hot tub stains can be your ticket to an exceptional spa experience, and the secret lies in understanding not just hot tub stain removal but also knowing how to prevent them in the first place. HTH will guide you in restoring your spa's former glory and ensuring it remains stain-free.

What Are The Common Causes Of Hot Tub Stains?

Even with diligent care, a hot tub brown stain or any other color, like yellow, can sometimes emerge. These unexpected blemishes often arise due to factors beyond just everyday dirt and grime. These factors include:

Calcium Build-Up

When the calcium content in the water is too high, it can lead to calcium build-up, commonly referred to as "hard water." As the water in the hot tub evaporates, the calcium ions get left behind and begin to accumulate. Over time, these deposits solidify and form chalky, white, or cloudy stains on the spa's surfaces.


When you notice a hot tub brown stain developing on your spa's surface, rust is often the culprit. Over time, metal components in or around your hot tub can corrode, releasing iron into the water.

This iron reacts with the water and chemicals, resulting in an unsightly hot tub brown stain. Additionally, using well water or other metal-rich water sources can introduce iron, which, when oxidized, results in rust stains.


Discovering a hot tub yellow stain can be alarming, and mold is often the offender. Given your spa's warm and moist environment, it provides an ideal breeding ground for mold.


Foam in your hot tub signifies an imbalance in your spa’s water chemistry. When body oils, lotions, or detergents mix with the water's chemicals, they create unsightly foam. This frothy layer can adhere to the sides and base of your hot tub, leading to staining over time.

HTH spa™ Care Test Strips: Spa Test Strips

Decoding Hot Tub Stains

Before we dive into the stain-busting process, it's crucial to grasp what's causing these unsightly marks in your hot tub. Hot tub stains come in a variety of hues, each indicative of a different underlying issue:

1. Hot Tub Yellow Stain: Often a sign of organic material buildup, such as mold, algae, or pollen. These stains often pop up when the hot tub water is out of balance. High pH levels, insufficient sanitization, or poor circulation can foster these unsightly yellow blots. Regular water testing and chemical adjustment are key to preventing and tackling yellow stains.

2. Hot Tub Brown Stain: Usually a result of metal deposits in the water, specifically iron or copper. These metals can oxidize and settle on the hot tub's surfaces, leading to discolored patches. Brown stains are common in areas with a high mineral content in the water supply. Specialized stain removers and metal sequestrants are often required to combat brown stains effectively.

3. Green or Blue-Green Stain: These hues typically suggest the presence of copper in the water. Copper can seep from pipes, fittings, or heating elements and cause these vibrant stains. Proper water chemistry maintenance and the use of a metal sequestrant can help keep these stains at bay.

4. Black or Gray Stain: Often the result of debris, organic matter, or even mold growth settling on the hot tub's surfaces. These stains can be unsightly and tough to remove. Regular cleaning and maintenance, along with appropriate sanitization, can help prevent them.

Determining the type of stain you're dealing with is crucial for choosing the proper hot tub stain removal method and maintaining a clean and inviting hot tub. By tackling the root cause and taking preventive measures, you can keep your spa looking its best for years to come.

HTH spa™ Care Clarifier: Hot Tub Clarifier

How To Prevent Hot Tub Stains

The haunting appearance of a hot tub yellow stain or the stubborn persistence of a hot tub brown stain can dampen the joy of your spa experience. That’s why you should invest in the following stain measures to maintain the pristine waters of your hot tub:

Regular Testing

You can use HTH care test strips to easily monitor the pH and alkalinity levels of your spa. If there’s an imbalance, use spa balancing chemicals like alkalinity up, pH up, and pH down products to tweak the levels until they're just right. A well-balanced hot tub provides a safer soaking environment and significantly reduces the likelihood of unsightly mineral deposits forming.

Use Clarifiers

HTH clarifiers can bind tiny particles, preventing them from settling and staining your spa. By introducing clarifiers to your regular spa maintenance routine, you ensure that these particles are kept in suspension until they can be effectively filtered out.

Sanitize Your Hot Tub Regularly

Regular sanitization is your frontline defense against the formation of a hot tub yellow stain and other discolorations. When you use products like HTH chlorinating sanitizer or bromine tabs, you ensure that unwanted organisms, which can lead to staining, are kept at bay.

HTH spa™ Care Defoamer: Spa Defoamer

Hot Tub Stain Removal: Steps To A Pristine Spa

If you’re already facing stain challenges, don't worry. Knowing how to remove hot tub stains can restore your spa's beauty and make it look as good as new. HTH is here to help guide you through the process of restoring your spa to its pristine glory:

How To Remove Hot Tub Yellow Stains

As we mentioned earlier, a hot tub yellow stain hints at mold or other organic matter accumulation. Fortunately, with the right approach, you can eliminate these stains. Here's how:

●  Drain and clean: Start by draining the water from your hot tub. This provides clear access to the stained areas, ensuring a thorough cleaning.

●  Sanitization: Apply a sanitizing solution, such as a chlorinating sanitizer, to treat the stained areas. The solution will break down organic contaminants and kill bacteria or algae, making the stains easier to tackle.

●  Scrub gently: Use a soft cloth or sponge to gently scrub the stained areas in circular motions, ensuring you don't scratch or damage the tub's surface.

●  Rinse and refill: After scrubbing, thoroughly rinse the hot tub to wash away the cleaning solution and dislodged stain particles. Refill your spa with fresh water.

How To Remove Hot Tub Brown Stains

A hot tub brown stain often indicates rust or high concentrations of iron or copper. Although these stains are stubborn, you can effectively remove them by following these steps:

●  Turn off the hot tub. To be doubly sure, switch off the hot tub breaker to ensure there's no electricity flowing to it.

●  Drain your hot tub completely to ensure you have complete access to all areas where the stains are most prominent

●  Use a cleaning product designed to tackle metal-related stains

●  Use a nylon sponge to gently scrub the stained areas thoroughly

●  Care for the hot tub filter by cleaning it using HTH filter cleaner. If it's too worn or clogged, consider replacing it.

●  Ensure a thorough rinse of the hot tub's shell to avoid foaming issues from residual cleaning agents

●  Re-examine the areas that had stains. If any marks persist, give them another scrub and rinse.

●  Refill your hot tub to the proper level provided by the manufacturer

●  Achieve the right water balance using HTH products like pH down, pH up, and alkalinity up

●  Conduct a water test using spa test strips and rebalance if required

●  Your hot tub is ready—time to relax and enjoy!

HTH spa™ Care Alkalinity Up: Spa Alkalinity Increaser

HTH Products for Stain Eradication

HTH offers top-quality products designed to keep your hot tub in impeccable condition. For hot tub stain removal, the HTH® Pool Care Metal, Stain & Scale Control is your reliable helper. Find this product and other HTH spa care essentials at the nearest HTH retailer. To locate one, use our store locator!

Hot Tub Stain Removal Made Easy

Maintaining a pristine and inviting hot tub involves knowing how to remove hot tub stains. Whether you're tackling a hot tub yellow stain or a pesky hot tub brown stain, having the right tools and products is imperative. HTH Pool and Spa stands out as the trusted choice for ensuring your spa remains in top-notch condition.

From pH balancers to clarifiers and defoamers, we have everything you need for a sparkling spa experience. Want to experience the HTH difference firsthand? Use our store locator to find the closest retailer with our exceptional product range and elevate your hot tub care routine today!

HTH spa™ Care Clear Chlorinating Sanitizer: Hot Tub Sanitizer

Want more?

If you have additional pool water care or product questions, we’re always here to help. Follow HTH™ Pool Care on social, reach out via our Chat feature or find a store near you.

Our Pool Opening page also has great into to make sure the start of the season goes swimmingly. You’re all clear with HTH®!

Need more help?

Live chat

Chat live with an HTH™ Helpline expert.

Chat now

Call us

Prefer to call us? We've got someone standing by daily from 9 a.m. – 7 p.m. ET, Monday – Friday