Pool Volume & Chlorine Calculator

Pool volume in m³, liters and gallons from its shape — plus how many grams of your chlorine product raise it by a target ppm.

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Always add chemical to water (never the reverse); the product label safety instructions govern. Do not swim until chlorine falls below 3-5 ppm.

Volume First, Then the Dose

Volume uses average depth (shallow + deep ends ÷ 2): rectangle = L × W × avg depth; round = π r² × depth; ovals ≈ 0.89 × L × W × depth. An 8×4 m pool averaging 1.5 m holds 48 m³ (48,000 L). The chlorine math is direct: 1 ppm = 1 gram of pure chlorine per m³ — raising 48 m³ by 2 ppm needs 96 g pure, which at 65% product strength (cal-hypo) means ≈ 148 g of granules.

Product strengths: trichlor tablets ~90%, dichlor granules ~56-62%, cal-hypo ~65-70%, liquid bleach ~12.5%. Keep free chlorine at 1-3 ppm routinely; shock to ~10 ppm weekly or after heavy use — and never swim until it falls back below 3-5 ppm.

Frequently Asked Questions

Why does my chlorine vanish so fast in summer?

UV sunlight destroys it within hours unless stabilized. Cyanuric acid (stabilizer) at 30-50 ppm shields it — but over ~100 ppm it locks chlorine up, and a partial drain is the fix.

The water is cloudy but chlorine reads fine — why?

Usually filtration or pH, not sanitizer: check pH 7.2-7.6, run the filter longer, backwash. High pH also makes chlorine sluggish even at good ppm.

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