A common mistake is believing that water balance is all about whether your pool has enough chlorine. In fact, the chlorine level has nothing to do with balanced water.
Balanced water in a nutshell, is water that is neither corrosive nor scale forming. Corrosive water will etch the surface of your pool and deteriorate the filtration equipment and fittings around your pool. Scale forming water will leave calcium deposits, staining the pools surface and potentially clogging pipes and filters.
The four factors that need to combine to create balanced water are: pH, Total Alkalinity, Calcium Hardness and Temperature.