Which substance should be used to lower the pH in a pool?

Sodium bisulfate is the appropriate choice for lowering the pH in a pool because it effectively introduces sulfates into the water, which reacts to lower the pH level. By adding sodium bisulfate, you can achieve the desired balance in water chemistry, making it safer and more comfortable for swimmers. Maintaining the correct pH is crucial not only for swimmer comfort but also for the effectiveness of sanitizers and the longevity of pool equipment.

In contrast, sodium bicarbonate is primarily used to raise the alkalinity, while sodium carbonate also serves to increase pH levels rather than lower them. Calcium hydroxide can raise both alkalinity and pH, which is not suitable for addressing high pH levels. Therefore, sodium bisulfate stands out as the ideal choice for managing and lowering pool pH effectively.