Raises water hardness level while preventing foaming and equipment corrosion. Convenient solution eliminates the need to predissolve crystals. Water low in calcium will corrode equipment. Maintaining proper hardness levels will extend the life of your spa. Compatible with chlorine, bromine, ozone and biguanide sanitizers. Applications: As Needed: One ounce raises the calcium hardness 7 ppm in 500 gallons of water. 1) Determine amount of product to be added. The ideal hardness level is 150-400 ppm. 2) Turn jets ON to circulate spa water. 3) Pour required amount into the water. 4) Run filter for 1 to 2 hours. 5) Retest water to ensure proper level. 6) Repeat steps 1-5 until proper level is obtained. Compatible With: Chlorine, bromine, ozone and biguanide sanitizers.