Type your test results; see how much chlorine, acid, baking soda, calcium, stabilizer or salt to add, for the product you bought.
Estimates. Follow the label on your product. Add one chemical at a time with the pump running, and never mix chlorine and acid — not in the bucket, not in the skimmer.
Pool volume (gal)
Don’t know it? Work it out from the size below.
Work out the volume from the size
Free chlorine (ppm)
Kills germs and algae. Keep it steady; more stabilizer needs more chlorine. Ideal 2–5
pH
Too low stings eyes and eats metal; too high clouds the water and slows chlorine. Ideal 7.2–7.8
Total alkalinity (ppm)
Holds the pH steady. Fix it before pH. Ideal 80–120
Calcium hardness (ppm)
Too low etches plaster; too high leaves scale. Ideal 200–400
Stabilizer (CYA) (ppm)
Shields chlorine from the sun. Only draining lowers it. Ideal 30–50
Water temperature (°F)
Optional. Only for the water balance.
Enter your pool volume first; the doses depend on it.
Add in this order, one at a time, with the pump running:
Example
1
Add 4.2 lb of baking soda
Alkalinity 80 → 100 ppm. Add it before you adjust pH.
2
Add 3¾ cups of muriatic acid
pH 7.8 → about 7.5. Approximate: add half, run the pump 30 minutes, retest.
Exactly 30.5 fl oz (902 ml).
3
Add 1 qt + ¾ cup of 10% liquid chlorine / bleach
Free chlorine 1 → 3 ppm.
Exactly 38.4 fl oz (1.14 L).
Water balance (LSI)
Add pH, alkalinity, calcium and water temperature to see the water balance.
Estimates. Follow the label on your product. Add one chemical at a time with the pump running, and never mix chlorine and acid — not in the bucket, not in the skimmer.
How it works
Test the water (strips or a drop kit), type each number you have, and the app lists what to add and how much, in the order to add it: alkalinity first, then pH, then chlorine, then calcium, stabilizer and salt.
Doses are worked out from the product strength on your label: 1 ppm in 10,000 gallons is 37.9 grams of chlorine, so 12.8 fl oz of 10 % liquid chlorine or 2 oz of 65 % cal-hypo. Baking soda: about 1.4 lb per 10 ppm of alkalinity. Calcium chloride: about 0.9 lb per 10 ppm.
Example: 15,000 gallons, free chlorine 1.0, target 3.0, 10 % liquid chlorine: add 1 quart + ¾ cup (38.4 fl oz). Add one chemical at a time with the pump running, and never mix chlorine and acid.
Frequently asked questions
How much chlorine do I add to my pool?
Multiply the ppm you need by your gallons and the strength of your product: 1 ppm in 10,000 gallons takes 12.8 fl oz of 10 % liquid chlorine, 21.3 fl oz of 6 % bleach or 2 oz of 65 % cal-hypo. The calculator does it for any pool.
Should I fix pH or alkalinity first?
Alkalinity first. It holds the pH steady, so adjusting pH before alkalinity means doing it twice.
Why is the pH dose only approximate?
How much acid moves the pH depends on the alkalinity and the starting pH. The app uses the health-department rule of thumb (12 fl oz of 35 % muriatic acid lowers 10,000 gallons by about 0.2): add half, run the pump 30 minutes and retest.