Calcium Hardness

Calcium hardness (CH) is the direct measure of the amount of calcium ions (Ca2+) in your pool water. Calcium hardness is different from total hardness (TH) or general hardness (GH) as those two parameters include magnesium hardness as well.

Magnesium ion concentration is mostly irrelevant for pool water and does not need to be included in hardness measurements.

CH, along with pH and TA, is one of the parameters needed to calculate the Calcite Saturation Index or CSI. The CSI tells you the degree to which your water is saturated with calcium carbonate.