Soda ash is the common name for sodium carbonate which can be used to adjust the pH and total alkalinity of a swimming pool. Swimming pools should have a pH between 7.4 and 7.6.
Water in swimming pools can become too acidic when the pH is too low leading to irritation for swimmers and issues for the pool itself including etching, corrosion of pipes, staining, and more. Sodium carbonate, or soda ash, can be added to quickly and effectively raise the pool pH to optimum levels. Interestingly, soda ash can be made at home by heating sodium bicarbonate, baking soda, in the oven where it will give off carbon dioxide and water leaving soda ash.