Decrease pH levels in pool water with our fast dissolving granular pool acid Ships in 2 Lbs.plastic container with safety capRecommended UseCheck pH levels weekly using a reliable spa test kitIf the pH level is more than 7.6 adjust the pH to 7.2-7.6 using pH MinusPool should be running with water being agitated when adding pH Minus to and should be left running for several hours thereafter to insure proper and thorough distribution