20,000 Gallon Pool Shock Calculator
Dosing Specifications for Standard 20,000 Gallon In-Ground Pools
A standard 20,000-gallon pool requires exactly 2 lbs (two bags) of 68–73% Calcium Hypochlorite or 1.6 gallons of 12.5% liquid chlorine to raise Free Chlorine by 10 ppm. For stubborn algae blooms, dose 6 bags after sunset.
Customize Your Pool Parameters
Adjust pool volume or shock severity to re-calculate instantly.
Granular shock. Fast-dissolving, adds zero CYA stabilizer.
Leaves zero residue, zero calcium, and zero CYA. 100% dissolved instantly.
Includes UV stabilizer. Ideal if your pool has low CYA (<30 ppm).
Avoid cheap big-box shock with low available chlorine (40–50%). Use 68–73% commercial Calcium Hypochlorite or 12.5% Sodium Hypochlorite for maximum algae kill rate.
20,000 Gallon Chemical Dosage Protocol
• Routine Maintenance: 2 bags Cal-Hypo OR 1.6 gal Liquid Chlorine.
• Heavy Swimmer Load / Rainstorm: 3 bags Cal-Hypo OR 2.4 gal Liquid Chlorine.
• Dark Green Algae: 6 bags Cal-Hypo OR 4.8 gal Liquid Chlorine.
Pre-Shock Chemical Checklist for 20k Gallons
Always test pH before shocking your 20,000-gallon pool. If pH is above 7.8, chlorine efficiency drops by more than 65%. Add 24–32 fl oz of muriatic acid to drop pH into the 7.2–7.4 sweet spot before introducing shock.