pH is a chemical measurement of acid or alkali in water.  Proper swim pool pH is 7.2 - 7.6; pH over 7.6 decreases chlorine sanitizing efficiency, pH under 7.0 is acid and is corrosive to metal.  If pH is too high or too low, eye, ear,nose, or skin irritation can occur.  Ideal pH is 7.2 - 7.6.

DAVIES "pH-PLUS" is added to raise pH in swim pools, and is generally used with gas chlorinators, slow dissolving chlorine tablets, and in special circumstances.  Use 1/2 lb. (equivalent to 8 fl. oz. measure) for 10,000 gal. of water for swim pool water with pH less than 7.0.  After 4 hours, check pH again and treat accordingly.