What is used to alleviate high pH levels in pool water?

Hydrochloric acid is used to alleviate high pH levels in pool water because it is a strong acid that effectively reduces the pH when added to the water. Maintaining the proper pH range, typically between 7.2 and 7.8, is crucial for the effectiveness of sanitizers like chlorine, as well as for comfort and safety for swimmers.

When pool water is alkaline and outside of this range, applying hydrochloric acid helps neutralize the excess alkalinity by introducing more hydrogen ions into the water. This process lowers the pH level, bringing it back within the ideal range for effective water quality management.

Other substances listed, such as chlorine tablets, are primarily used for disinfection rather than pH adjustment. Baking soda is used to raise pH or increase alkalinity, and calcium chloride is applied to increase calcium hardness in pool water. Therefore, these options do not serve the purpose of directly reducing high pH levels, making hydrochloric acid the appropriate choice for this task.