What chemical is often used to lower pH levels in pool water?

Sodium bisulfate is commonly used to lower pH levels in pool water due to its acidic properties. When added to water, it dissociates to release hydrogen ions, which effectively decreases the pH level. Maintaining proper pH levels is critical for pool water balance, ensuring that the water is safe for swimming, prevents corrosion of equipment, and optimizes the effectiveness of chlorine disinfectants.

In contrast, the other chemicals listed have different primary functions. Calcium carbonate is typically used to raise pH levels and increase total alkalinity, making it unsuitable for lowering pH. Aluminum sulfate is mainly used as a coagulant in water treatment processes but is not meant for adjusting pH levels effectively. Potassium chloride is generally used to increase salinity or as a salt substitute rather than for adjusting pH. Thus, sodium bisulfate is the right choice for lowering pH in pool water.