The pH levels of swimming pools are recommended to be at 7.2 to 7.6. If the pH is too low (acidic), it may cause skin irritations, and corrode equipment. At high pH, there may be build up of scale, which will result in the water being cloudy. The effectiveness of Chlorine as a disinfectant is also determined by pH levels of the water.
Conductivity and TDS (Total Dissolved Solids) are also parameters tested. Chemicals added to adjust pH, dust, etc affects TDS. The max acceptable TDS level is 1,500 ppm. Above this level, there may be staining and cloudiness in pool.
The parameter, ORP (Oxidation Reduction Potential), also determines the effectiveness of Chlorine being added to the pool as disinfectant.