🪨 Calcium Chloride (77%)
granular calcium chloride flake, ~77% · updated August 2026
Quick answer: add 19.2 oz per 10,000 gallons to raise Calcium Hardness 10 ppm. Ideal Calcium Hardness: 200–400 ppm. Add ½–⅔ first, circulate, retest.
Safety — read first
- • Pre-dissolve in a bucket (it heats up — use cold water, stir, let it cool).
- • Add in doses of no more than 10 ppm at a time.
Protects plaster and equipment: water below ~200 ppm calcium is aggressive and pulls calcium out of plaster, grout and heat exchangers.
Side effects: Gets hot when dissolving. Like CYA, there's no reducer — only dilution with fresh water.
Dosing chart
| Pool size | +10 ppm | +20 ppm | +30 ppm | +50 ppm |
|---|---|---|---|---|
| 5,000 gal | 9.6 oz | 1.2 lb | 1.8 lb | 3.0 lb |
| 10,000 gal | 1.2 lb | 2.4 lb | 3.6 lb | 6.0 lb |
| 15,000 gal | 1.8 lb | 3.6 lb | 5.4 lb | 9.0 lb |
| 20,000 gal | 2.4 lb | 4.8 lb | 7.2 lb | 12.0 lb |
| 30,000 gal | 3.6 lb | 7.2 lb | 10.8 lb | 18.0 lb |
Calculate your exact dose
1 · Your pool's volume
Working with 20,000 gallons
2 · What are you fixing?
Ideal Calcium Hardness: 200–400 ppm. Adjusting pH? Doses aren't linear — see soda ash / muriatic acid.
3 · Add one of these
Estimates from standard label dosing, to raise Calcium Hardness by 100 ppm in 20,000 gallons. Add ½–⅔ of the dose first, circulate 4–6 hours, retest, then top up. Never mix chemicals with each other.
FAQ
How much calcium chloride do I add per 10,000 gallons?+
19.2 oz per 10,000 gallons will raise Calcium Hardness 10 ppm. Scale linearly with your pool size — the chart on this page covers 5,000 to 30,000 gallons.
What does calcium chloride do to a pool?+
Protects plaster and equipment: water below ~200 ppm calcium is aggressive and pulls calcium out of plaster, grout and heat exchangers. Side effect to know: Gets hot when dissolving. Like CYA, there's no reducer — only dilution with fresh water.
Is calcium chloride safe to handle?+
Pre-dissolve in a bucket (it heats up — use cold water, stir, let it cool). Add in doses of no more than 10 ppm at a time.