When pH value rises above 7.8 while the pump is in operation, distribute 4-ounce for each 10, 000-gallon of water into the deep end of the pool * Allow 6 to 8 hours for distribution throughout the pool, and then recheck the ph * Sanitizers work most efficiently when pH is kept in proper range * Comparable with chlorine, bromine, ozone, biguanide sanitizers, and salt water pools * Measures 10-inches in height 4.3-inches in width by 4.3-inches in length