Spa Calcium Hardness Increaser

Bring your calcium into ideal range

Natural Chemistry’s Spa Calcium Hardness Increaser is used to raise calcium hardness in spa water. Calcium hardness in spa water should be maintained between 150-250 ppm. Low calcium hardness levels could cause the spa water to be corrosive which may result in damage to the spa surface or equipment.


– Brings calcium hardness level to an ideal range
– Reduces cloudy water caused by low calcium levels

1.75 lb. cannister


1. Test spa water for calcium hardness level.
2. Compare test results to chart below to determine appropriate amount of Natural Chemistry Spa Calcium Hardness Increaser necessary to make adjustment.
3. With spa circulating pump on high speed, add required amount directly into spa water. Continue circulating water a minimum 20 minutes. Do not pre-dissolve this treatment as heat is generated when it contacts water.
4. Retest and adjust if necessary.

Dosage Chart 
(All values are in dry ounces)

Spa Volume20ppm40ppm80ppm100ppm
200 gal.751.533.75
400 gal1.5367.5
800 gal361215

NCI threaded safety cap = 1/2oz
NCI large over cap = 4oz