Hot tub and spa chemicals Sanitiser: This helps to kill bacteria and other microorganisms that can build up in the water. Chlorine and bromine are the most common types of sanitiser used in hot tubs. pH balancer: Hot tub water should have a pH level between 7.2 and 7.8. If the pH is too low, the water can become acidic and irritate the skin and eyes. If the pH is too high, the water can become basic and cause the sanitiser to be less effective. You can use pH plus or pH minus and adjust the pH to the proper range. No-foam: This chemical helps reduce the amount of foam that can sometimes form in hot tub water.