Rendezvous Spa Specialties Liquid Calcium Hardness Up increases hardness in spas and hot tubs in areas with low levels of hardness. This product prevents corrosion of plumbing and equipment. It is an easy-to-use liquid product. Avoid low hardness that will etch plaster and corrode equipment. Liquid Calcium Harness Up is compatible with chlorine, bromine, ozone, and mineral purification systems.
1 fl oz per 500 gallons of water will raise hardness by 7 ppm.
- Determine amount of Liquid Calcium Hardness Up to be added using a hardness test kit.
- Pour proper amount into spa or hot tub with equipment turned on.
- Run filter for 1-2 hours.
- Water may be re-tested in 20 minutes.
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