If the calcium hardness of pool water is low, which chemical should be used to raise it?

Calcium Chloride is the correct choice for raising the calcium hardness of pool water. Calcium hardness is an important aspect of pool water chemistry, as it helps to prevent corrosion of pool equipment and surfaces, as well as to stabilize the overall water balance.

When calcium hardness levels are low, it can lead to issues such as corrosion of metal fixtures and surfaces, as well as difficulty in maintaining appropriate pH levels. Adding Calcium Chloride increases the calcium content in the water effectively. This compound dissolves in water, releasing calcium ions, which raises the hardness level appropriately.

Muriatic acid is used primarily to lower pH and alkalinity, not to increase calcium hardness. Sodium Bicarbonate is useful for raising total alkalinity and pH, but it does not add calcium to the water. Sodium Thiosulfate is typically used as a dechlorinator and does not affect calcium levels either. Therefore, Calcium Chloride serves the specific purpose of correcting low calcium hardness levels in pool water.