How much liquid chlorine should I add to my pool?

A worked example

For a 15,000-gallon chlorine pool with 2 ppm FC, 40 ppm CYA, and 10% liquid chlorine, the target starts at 6 ppm FC. Raising FC by 4 ppm takes about 77 fluid ounces of 10% liquid chlorine.

(6 − 2) ppm × (15,000 ÷ 10,000) × 128 ÷ 10 = 76.8 fl oz

How the estimate works

The FC target depends on CYA: stabilizer protects chlorine from sunlight, but more CYA also means you need more FC. The calculator uses the same FC/CYA target table as ChemCoach. It rounds CYA to the nearest 10 ppm for the target, uses a separate target for salt chlorine generator pools, and doses to the low end of the target band.

One gallon of 10% liquid chlorine raises FC by about 10 ppm in 10,000 gallons. The estimate scales with pool volume, desired FC increase, and bottle strength. Actual results vary with chlorine age, sunlight, and water conditions. Re-test after circulation and adjust from the measured result.

Before adding chlorine

Use a reliable drop-based test and your best pool-volume estimate. Check the product label, keep the pump running, add one chemical at a time, and never mix pool chemicals. This tool covers routine dosing of residential pools with CYA readings up to 100 ppm; higher CYA, green or cloudy water, high combined chlorine, and other water problems need a full water assessment. It does not determine whether water is safe to swim in.