How much calcium chloride raises hardness?

About 1.25 lb of calcium chloride per 10,000 gallons raises calcium hardness ~10 ppm. Enter your numbers for the exact dose.

What's the ideal calcium hardness?

200–400 ppm for plaster/gunite; 150–250 ppm is fine for vinyl or fiberglass.

How do I lower calcium hardness?

There's no chemical for it — partially drain and refill with lower-calcium water, or use a reverse-osmosis service.

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Pool Calcium Hardness Calculator

Too little calcium and soft water etches plaster and corrodes metal. Enter your reading and surface type for the right calcium chloride dose.

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Balance your whole pool at once →Enter all your readings on one screen and get an ordered dosing plan — the full Water Report.

How to use it

Test calcium hardness.
Pick your surface (plaster needs more calcium than vinyl/fiberglass) and enter your volume.
Pre-dissolve calcium chloride in a bucket of water, then pour around the pool with the pump running.

Why surface type changes the target

Plaster and gunite pools need 200–400 ppm calcium — the water will pull calcium out of the plaster itself if it's starved. Vinyl and fiberglass don't have calcium to protect, so they only need enough (around 150–250 ppm) to keep the water balanced. Use the surface selector so you don't over- or under-dose.

Frequently asked questions

How much calcium chloride raises hardness?: About 1.25 lb of calcium chloride per 10,000 gallons raises calcium hardness ~10 ppm. Enter your numbers for the exact dose.
What's the ideal calcium hardness?: 200–400 ppm for plaster/gunite; 150–250 ppm is fine for vinyl or fiberglass.
How do I lower calcium hardness?: There's no chemical for it — partially drain and refill with lower-calcium water, or use a reverse-osmosis service.

Related calculators

Built & reviewed by a working pool-service pro. Target ranges follow CDC MAHC, PHTA, and Taylor guidance. Doses are starting estimates — add a little less than the max, re-test, and confirm against your product label. Educational tool, not a substitute for a water test or professional advice.