4 Things to Know About Adding Calcium to Your Pool

Soft fill water requires manual calcium addition If your water is naturally soft, it will aggressively dissolve minerals from plaster, grout, or your heater. You must raise calcium hardness to prevent damage.

Target 200–400 ppm calcium hardness Use a test kit or strip to measure. If you are well below that range, you need to add calcium chloride.

Use straight calcium chloride, not fancy blends Buy a bucket of “hardness increaser” at a pool store. Dissolve it in a bucket of pool water, then pour it near a return jet with the pump running. Follow the label dosage—about 1 pound per 10,000 gallons raises hardness by 10 ppm.

Check calcium hardness only a couple times per season You do not need to test weekly. Check after a heavy rain or refill, but otherwise it is low maintenance.