Answer:

pH - This is the most critical water balance parameter. The lower the pH, the more acidic and aggressive the water. Higher pH means alkaline or basic water and can be scale forming. Balancing the pH prevents corrosion and scale build-up on equipment. It also helps your other chemicals work properly to keep the water clean and clear and protects the swimmers' skin and eyes from irritation. Un balanced pH is a very common cause of cloudy water.