Dry acid is added to the pool water to balance the pH. Typically sodium bisulfate, it comes in a dry, granulated form.
Sodium bisulfate is formed by the partial neutralization of sulfuric acid, using either sodium hydroxide or sodium chloride. Like any acid, it should be handled with care.
Because chlorine can become unstable when exposed to ultraviolet light, most chlorine compounds added to pool water are stabilized. In some conditions, the pH of the water can then become too high. This results in scaly formations on the pool walls, floor and fixtures, as well as cloudy water. In addition, the chlorine is less effective. To prevent or counter these effects, dry acid or sodium bisulfate is added to the water. This balances the pH of the water.
To add dry acid to the pool, set the pump on filter. Dissolve the dry acid in a bucket of water, according to the manufacturers instructions. Then pour the contents into the deepest part of the pool.
Like any acid, dry acid should be handled with care. Wear protective gear, including mask, goggles and clothing, while handling. Inhaling dry acid fumes can cause irritation of the lungs or mucous membranes, which can lead to lung edema or fluid buildup in the lungs. If ingested, severe internal burns and vomiting can result. In addition, contact with the skin and eyes can cause burns. If exposed to dry acid, seek medical attention immediately. Flush the skin or eyes with water or drink water, but do not induce vomiting.
Dry acid should be stored in its original, labeled container, in a dry, well-ventilated area.