Hardness Increaser

10 lb.  |  25 lb.  |  50 lb.

Dry granular or flake product to raise calcium hardness in pool water. Prevents etching of plaster in concrete pools due to low calcium hardness levels.

To add calcium hardness to the pool, broadcast evenly over the pool water with the filter running.

Calcium hardness normally should range between 180 to 250 ppm for vinyl liner pools, and 200-275 ppm for gunite pools. However, calcium hardness must be in balance with total alkalinity to prevent a scale forming or a corrosive condition. A test kit should be used to determine both total hardness and total alkalinity. Most test kits have charts indicating balanced conditions at various levels. If additional hardness is indicated, the use of 1 lb. of this product will raise the total hardness of 10,000 gallons of water by 8.0 ppm.

To calculate the amount of this product needed to raise calcium hardness use the following formula:

To increase calcium hardness using calcium chloride dihydrate (CaCL2,2H20)

Desired Calcium Increase 1,000 gal 5,000 gal 10,000 gal 25,000 gal
10 ppm 2 oz. 10 oz. 1.25 lbs. 3.2 lbs.
25 ppm 5 oz. 1.6 lbs. 3.2 lbs. 8 lbs.
50 ppm 10 oz. 3.2 lbs. 6.4 lbs. 16 lbs.


16 ounces = 1 pound      |      1 ounce = 28.35 grams

MSDS Sheets (pdf)