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.