GLB Pool and Spa Products 71246 4-Pound pH Up Pool Water Balancer When ph falls below 7.2 while the pump is in operation distribute ph up into the deep end of the pool For every 10, 000-gallon of water use 1-pound when ph is below 6.6; 3/4-pound when ph is between 6.6 and 7.0; 1/2-pound when ph is between 7.0 and 7.3 Keeping proper ph levels will help ensure pool sanitizers are working at maximum efficiency and aids in preventing staining, scaling and clouding Comparable with chlorine, bromine, ozone, biguanide sanitizers, and salt water pools Measures 9.6-Inches in height by 4.6-Inches in length by 4.6-Inches in width