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Taylor K-2006 Complete DPD-FAS Pool Test Kit
Lab-grade titration kit for accurate Free Chlorine, Total Alkalinity, Calcium & Cyanuric Acid.
How to Lower Calcium Hardness in a Pool (And Prevent White Scale)
Run your fingers along your pool tile line or gunite plaster floor. If it feels rough like coarse sandpaper or has a chalky white film, your water is super-saturated with Calcium Hardness (CH > 500 ppm).
High calcium ruins expensive gas heater heat exchangers, clogs salt chlorinator cell plates with white rock, and clouds water on hot sunny afternoons. Because calcium does not evaporate, summer evaporation continuously concentrates minerals into dangerous scaling territory.
0MS CALCIUM DILUTION ENGINE
Calcium Hardness Drain & Refill Calculator
Calculate the exact percentage and gallons of high-calcium water to replace with fresh tap water to bring your pool back to the 250 ppm safe equilibrium.
WATER TO DRAIN
55% Drain
8,250 GallonsTARGET POST-REFILL
250 ppm CH
Zero scale precipitationLSI TARGET PH CEILING
7.3 - 7.5 pH
Keeps minerals dissolvedSALT CELL SCALING
Prevented
Saves $950 replacementADVERTISEMENTSponsored
01Test Your Fill Water First
Before draining a single drop of pool water, test your garden hose tap water with a calcium titration kit. In areas like Southern California or Texas, municipal tap water often has 200–300 ppm calcium out of the faucet. You can only dilute down to the baseline hardness of your fill source.
02Stop Using Cal-Hypo Granular Shock Immediately
Every 1 pound bag of Calcium Hypochlorite (Cal-Hypo) shock you dissolve dumps 6.0 ppm of permanent calcium into 10,000 gallons of water. If your calcium is already elevated, switch strictly to liquid chlorine (sodium hypochlorite), which adds zero calcium hardness.
03Manage the LSI (Keep pH at 7.3–7.5)
If a full water drain is not immediately feasible (e.g., in drought-restricted regions or high water-table zones where pools can pop out of the ground), you can temporarily prevent scaling by strictly running your pH at 7.3 to 7.4. Lower pH increases water's acidity, holding excess calcium dissolved in liquid suspension rather than depositing on tile.
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Need to Calculate Total Water Saturation (LSI)?
Calcium hardness is a key pillar of the Langelier Saturation Index. Use our 0ms dynamic water balance engine to calculate exact chemical additions for your pool and protect equipment.
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