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

Sodium carbonate, commonly known as soda ash, is widely recognized for its ability to effectively increase the pH levels of pool water. Pools typically require a pH range between 7.2 to 7.8 for optimal comfort and efficiency. When the pH falls below this range, it becomes necessary to raise it to maintain a safe and pleasant swimming environment.

Soda ash works by dissolving in water to release hydroxide ions, which raises the pH levels. This adjustment is vital because low pH can result in corrosive conditions that can damage pool surfaces and equipment, as well as cause skin and eye irritation for swimmers.

In contrast, the other chemicals listed do not serve the same purpose effectively. Calcium chloride primarily functions as a calcium source and is used to increase water hardness rather than to raise pH. Aluminum sulfate is typically employed as a coagulant for settling particulates in water but does not impact pH levels significantly. Trisodium phosphate can adjust pH but is more commonly used in specific cleaning or sanitizing applications rather than as a general pH increaser in pool maintenance.