Which chemical is commonly used to increase the pH level in pool water?

Sodium carbonate, often referred to as soda ash, is a chemical widely used to raise the pH level in pool water. Maintaining the proper pH balance in a swimming pool is crucial for water clarity, comfort for swimmers, and the effectiveness of sanitizers. When the pH level of pool water is too low, it can lead to corrosion of metal components and skin and eye irritation for swimmers.

Sodium carbonate works effectively because it is a strong alkaline substance that, when added to water, raises the pH levels. This allows pool operators to adjust the pH towards the ideal range of 7.2 to 7.8, ensuring the water is safe and comfortable for swimmers.

In contrast, the other choices serve different purposes: sodium bicarbonate is primarily used to raise alkalinity rather than pH; calcium hypochlorite is a chlorine compound used for sanitization; and aluminum sulfate is commonly used as a coagulant in water treatment, rather than for adjusting pH levels. This highlights the specific role of sodium carbonate in managing the chemical balance in pool water effectively.