For swimming pools and spas the ideal pH level is 7.5, which being slightly alkaline protects the pool finish and support equipment from being attacked by acid.

A pH of 7.5 also creates the most comfortable bathing conditions as it is the pH of the human eye.

Another reason for maintaining a pH level of 7.5 is for chemical efficiency, particularly chlorine. If the pH level wanders too high then the effectiveness of chlorine is greatly reduced. At a pH of 8.2, chlorine is 5 times less effective than it is at a pH of 7.5.

High pH levels can also make pool water look cloudy as calcium precipitates out of the water and remains suspended in the water. This can  lead to scale deposits on the pool shell, within pipework and within plantroom equipment.

Within the BioGuard range there are products to correct pH levels. BioGuard Lo 'n' Slo is used to lower high pH levels and BioGuard Balance Pak 200 raises low levels.