Pool Basics 2825PB Calcium Hardness Increaser for Pools, 25-Pound
Pool Basics Calcium Hardness is used to raise calcium hardness levels when measures drop below the recommended range of 200-400 ppm. If calcium hardness levels are too low the "soft water" will corrode pool equipment, etch pool plaster and may cause metallic stains. To raise the hardness level by approximately 50ppm is necessary to add 6.25 lbs. per 10,000 gallons of pool water.