Robelle 4 lbs. Calcium Plus Hardness Increaser for Swimming Pools

Robelle Calcium Plus 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 Gal. of pool water.