Plaster & Surface Protection
Pool Calcium Hardness Dosing Calculator
Calculate exact pounds and kilograms of Calcium Chloride needed to protect your pool plaster, tile grout, and heating elements from corrosive water damage.
Calcium Hardness Dosing Engine
Calculate Calcium Chloride needed to protect plaster
10,000 gal
150 PPM
300 PPM
Required Calcium Chloride+150 PPM Boost
77% Calcium Chloride Flakes
22.5 lbs
(10.21 kg)
Recommended Hardness Increaser
Use commercial grade Calcium Chloride flakes to raise hardness without clouding water.
Check Calcium Hardness Increasers on AmazonPre-Dissolving Precaution:
Always pre-dissolve calcium chloride in a 5-gallon bucket of water before pouring into the pool. Calcium generates heat when reacting with water.
Calcium Chloride Dosing Formula
To raise Calcium Hardness by 10 PPM in a 10,000-gallon pool, add 1.2 lbs of 100% Calcium Chloride (or 1.5 lbs of 77% Flake).
Calcium Chloride 77% (lbs) = (Pool Gallons ÷ 10,000) × (Target CH − Current CH) × 0.15Related Water Balance Tools
Frequently Asked Questions About Calcium Hardness
Guidelines on maintaining proper calcium levels to extend pool surface lifespan.
For plaster, gunite, and concrete pools, ideal Calcium Hardness is 250 to 350 PPM. For vinyl liner and fiberglass pools, ideal Calcium Hardness is 175 to 250 PPM.
Low calcium hardness (under 150 PPM) makes water aggressive. Corrosive water dissolves calcium directly out of plaster and concrete walls, causing pitting, rough surfaces, and tile grout erosion.
Add Calcium Chloride (either 77% flake or 94% anhydrous pellets). Dissolve it in a bucket of water first, as calcium chloride generates heat when mixed with water.
Calcium does not evaporate. The only reliable way to reduce high calcium hardness is to partially drain the pool and refill with fresh tap water.