GLB PH Down lowers the pH level in swimming pool water. This product aids in preventing staining, scaling, and clouding of pool water. Sanitizers work most efficiently when pH is kept in proper range. Therefore a properly balanced pool will require less sanitizer and less pool maintenance. Keeping your pool water balanced is an important step in getting the most out of and preserving the life of pool equipment. PH Down can be used with chlorine, bromine, ozone, biguanide sanitizers, and salt water pools.