Which chemical is used to decrease the pH in pool water?

Sodium bisulfate is utilized to decrease the pH in pool water because it acts as an acid when dissolved, providing the necessary hydrogen ions that lower the pH level. Maintaining the proper pH balance is crucial in swimming pools as it ensures optimal sanitizer effectiveness, prevents corrosion of pool equipment, and promotes swimmer comfort. When the pH is above the ideal range (typically between 7.2 and 7.8), the addition of sodium bisulfate helps to bring it back into that range efficiently.

In contrast, sodium carbonate raises the pH level, while calcium chloride is primarily used for increasing calcium hardness in water and does not directly affect pH. Polyethylene glycol is not relevant in the context of pH adjustment for pool water; it's generally used as a thickening agent or in other non-pool-related applications.