Surface Protection: Why Calcium Balance Is Non-Negotiable
Plaster and cementitious pool finishes are largely composed of calcium carbonate. When water lacks dissolved calcium, it reaches equilibrium by dissolving the walls of the pool, resulting in rough sandpaper-like surfaces and chipped plaster.
Safely Dissolving and Adding Calcium Chloride
Calcium chloride releases significant heat when dissolved. Never add water to dry chemical! Always fill a clean bucket 75% full of pool water first, add no more than 5 lbs of calcium chloride at a time, stir thoroughly until clear, and pour around the deep end perimeter.
Frequently Asked Questions
What is the ideal Calcium Hardness level for a swimming pool?
For plaster, gunite, and pebble-tec pools, ideal Calcium Hardness (CH) is 250 to 350 ppm. For vinyl and fiberglass pools, a lower level of 150 to 250 ppm is recommended to prevent foaming and protect metal fittings without risking scale.
Why does low calcium hardness damage plaster pools?
Water has a natural affinity for calcium. If water is deficient in calcium, it will dissolve calcium hydroxide from pool plaster and tile grout, causing pitting, roughness, and surface degradation.
How do I raise Calcium Hardness in my pool?
Add Calcium Chloride (either 100% anhydrous pellets or 77% flake). Approximately 1.25 lbs of 100% calcium chloride raises 10,000 gallons by 10 ppm. Always pre-dissolve calcium chloride in a bucket of cold water before adding, as it produces an exothermic heat reaction.
How do I lower high Calcium Hardness?
Calcium cannot be lowered chemically. The only permanent method is to drain a percentage of the pool and refill with fresh water lower in calcium.