What chemical is used to raise the pH level in pool water?

Sodium carbonate, commonly known as soda ash, is the chemical used to raise the pH level in pool water. When added to the water, it increases the alkalinity, thereby helping to elevate the pH. Maintaining an appropriate pH level is crucial for several reasons: it ensures swimmer comfort, prevents corrosion of pool equipment, and maintains the efficacy of chlorine for disinfection.

Soda ash is particularly effective because it not only increases pH but also contributes to the overall alkalinity of the pool, providing a buffer that stabilizes the water chemistry. This dual action helps to maintain a consistent pH level, reducing the need for frequent adjustments.

Other chemicals listed do not serve the same purpose in a swimming pool. For instance, alum is primarily used as a coagulant, calcium chloride is used to raise calcium hardness, and potassium sulfate serves as a source of potassium and sulfate ions without significantly affecting pH. Understanding the specific role of these chemicals helps ensure that pool operators can effectively manage water chemistry for optimal pool conditions.