High pH can cause extensive scaling and damage to the pool interior finish if not correctly balanced on a weekly basis. The acceptable range for pH is 7.2 - 7.8 but the optimum comfort level for pH would be 7.4 as this is the closest point to the pH level of human teardrops at 7.35.
Ph will fluctuate naturally especially if the Alkalinity is out of range.
High pH can be reduced by the addition of Hydrochloric Acid, commonly referred to as Muriatic Acid. Hydrochloric Acid adds hydrogen ions H+ to the pool water thereby reducing the pH range of that body of water.
Bob Charlton is a Certified Pool & Spa Operator and Inspector with the National Swimming Pool Foundation with 15 years of experience of pools in Florida.