Pool Chemical Calculator
Pick an adjustment -- chlorine, pH or alkalinity -- and get a dose for your pool's volume.
Dose Needed
Not sure whether salt or traditional chlorine is right for your pool? Take the Salt or Chlorine Finder.
Take the quizHow these pool chemical doses are calculated
These are the standard rule-of-thumb dosing rates used throughout the pool-care industry, each scaled to your exact pool volume in 10,000-gallon increments: raising free chlorine by 1 ppm takes about 10 fl oz of 12.5% liquid chlorine, 2 oz of 65% cal-hypo, or 2.5 oz of 56% dichlor, per 10,000 gallons.
Raising pH by about 0.2 takes roughly 6 oz of soda ash (sodium carbonate) per 10,000 gallons; lowering pH by about 0.2 takes roughly 8 fl oz of muriatic acid (31.45% strength) per 10,000 gallons. Raising total alkalinity by about 10 ppm takes roughly 1.5 lb of baking soda (sodium bicarbonate) per 10,000 gallons.
These rates are estimates published widely by pool-supply retailers and chemical manufacturers -- actual results vary with your water's starting chemistry, temperature and how thoroughly the chemical circulates, so always test after dosing and adjust rather than dosing the full estimated amount all at once for a big change.
Safety: Always add chemicals to water, never water to chemicals -- this is especially critical for muriatic acid, which can splash and react violently if water is added to concentrated acid. Add slowly with the pump running, and keep all pool chemicals away from children and pets.
Dosing a spa instead of a full pool? Use the hot tub chemical calculator, which applies the same rule-of-thumb rates to hot tub-scale volumes.
Where these numbers come from
The formulas and default values in this calculator are based on:
- standard rule-of-thumb pool chemical dosing rates published by pool-supply retailers and chemical manufacturers (chlorine: ~10 fl oz 12.5% liquid, ~2 oz 65% cal-hypo, or ~2.5 oz 56% dichlor per 10,000 gal per 1 ppm FC
- pH: ~6 oz soda ash raises pH ~0.2 per 10,000 gal, ~8 fl oz muriatic acid (31.45%) lowers pH ~0.2 per 10,000 gal
- alkalinity: ~1.5 lb baking soda per 10,000 gal raises TA ~10 ppm)
These are planning estimates. Test your actual water, follow product labels, and check your equipment manufacturer's guidance before you buy or dose chemicals.
Frequently asked questions
Which chlorine type should I pick?
Liquid chlorine (12.5%) is common for larger pools and pairs well with a saltwater system as an occasional boost; cal-hypo is a common granular shock chlorine; dichlor is popular for smaller doses and spas because it's stabilized and dissolves easily. Any of the three works for raising FC -- pick whichever you already have on hand.
Why does the alkalinity dose use a different base amount than chlorine?
Each chemical reacts differently in water, and total alkalinity changes are measured in whole ppm rather than fractions, which is why baking soda's rate (1.5 lb per 10,000 gal per 10 ppm) is expressed differently than chlorine's per-1-ppm-per-10,000-gal rate. Both are just the industry-standard units for each measurement.
Should I adjust pH or alkalinity first?
Most pool professionals recommend correcting alkalinity first, since it acts as a buffer that stabilizes pH -- fixing pH before alkalinity is often undone once alkalinity is adjusted afterward. Test both, fix alkalinity, wait a day, then re-test and adjust pH if it's still off.
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