Leisure Time Protectant Calcium Booster (30220A) Maintain a hardness level of 150-400 ppm Compatible with chlorine, bromine, ozone and biguanide sanitizers For more than 25 years, Leisure Time has been the premier name in spa water care Compatible with chlorine, bromine, ozone and biguanide sanitizers One ounce increases hardness 7 ppm in 500 gallons of water Prevents corrosion