If an Alkalinity test shows the Alkalinity level to be too high, then the Alkalinity must be lowered. There are two chemicals to lower Alkalinity-the same chemicals that lower pH (Sodium Bisulfate or muriatic acid) will also lower Alkalinity.
With a pH tester, measure the water’s pH. The proper pH for a pool is in the range of 7.2 to 7.6.
To lower the pH, add sodium bisulfate or liquid muriatic acid. To raise it, add soda ash (sodium carbonate).