DescriptionpH Increaser for hot tubs strongly raises both the pH and Total Alkalinity (TA) of spa water. Reduces corrosion damage to metal parts, pump motors and heaters caused by low pH. Reduces eye irritation caused by low pH. Balanced water can improve the effectiveness of sanitizers. Fast-dissolving form for spas Strongly raises TA Strongly raises pH Product notes: Check spa water with test strips to achieve balance. Adjust Total Alkalinity (TA) first, then adjust for proper pH range. Proper TA will buffer pH, preventing pH fluctuations. Contains 100% granular sodium carbonate, pH 13 (also referred to as soda ash -- not to be confused with sodium bicarbonate). If your pH is normal or slightly low, and/or you primarily want to raise TA, use Alkalinity Up instead.