To balance the pH levels in a hot tub, users must first measure the pH level and then add either an alkalinity increaser or a pH decreaser as needed to equalize the water. Balancing the pH is important to prevent corrosion due to acidity, or build-up of film and scales on the sides of the tub due to alkalinity.
The pH level of a hot tub can be tested with pH test strips or a meter. A low pH level indicates the water is acidic, while a high pH level indicates alkaline. Tap water and distilled water may have a wide range of pH levels, so it's important to test a hot tub weekly, as well as whenever the water source is changed. The total alkalinity for the water of a hot tub should be between 80 and 120 parts per million (ppm), while the pH level should be between 7.2 and 7.6.
If either of these numbers are outside the given ranges, users will need to balance the water by adding the appropriate chemicals, provided in most hot tub maintenance kits, as well as offered by spa and pool suppliers. An alkaline increaser should be added when the total alkalinity is low, while a pH decreaser will lower high-alkaline pH levels.
After adding the appropriate chemicals, wait a minimum of 24 hours before checking the pH levels again to give the water time to equalize. If the levels are still off, add more chemicals as needed, until the hot tub is at the optimal pH.