Pool water that has a high pH, or is too alkaline, can promote the growth of scales on the surface of the water and pool equipment, which can result in cloudy water. Very alkaline pool water also disrupts the efficacy of pool equipment and may prevent disinfectant from working optimally.
Pool equipment and chlorine require a particular pH range to function properly. A low pH, which denotes acidity, is equally harmful, as it corrodes surfaces and equipment. Adding acid to pool water helps to lower the pH of pool water that is too alkaline.
Liquid hydrochloric acid and dry sodium bisulphate are the two most common acids that pool owners and experts use to lower the pH of pool water. Sodium bicarbonate, otherwise known as baking soda, is another viable acid that adjusts the pH of water.
Purveyors of pool supplies often refer to pool acid products as pH minus, ph decreaser or pH reducer. On the standard pH scale of zero to 14, where zero denotes the most acidic and 14 the most alkaline, pool water should be neutral, or between roughly 7.2 and 7.8.
It is advisable to test pool water before applying any acid, whether liquid or dry, and to not allow more than 24 hours to elapse between applications. While liquid acid products occasionally require diluting with water before application, most dry acids are ready to be applied right out of the package.