The doses come from the Arkansas Department of Health's dosage chart for pool operators, checked against the CDC's Model Aquatic Health Code and an Indiana state guide. Each chart gives the amount that changes ten thousand gallons by a set number of ppm, and the calculator scales it to your pool and the change you need.
How to use this calculator
- Enter the pool volume in gallons. The pool volume calculator works it out if you do not know it.
- Choose what to do: raise free chlorine, raise or lower total alkalinity, raise calcium hardness, or raise stabilizer.
- Pick the product and its strength from the label.
- Enter your test reading and the target, then add the amount in steps and retest.
Worked examples
Raising chlorine with liquid chlorine
Pool volume: 15,000 · What to do: Raise free chlorine · Product: Liquid chlorine, 10% · Reading now: 1 ppm · Target: 3 ppm
- Liquid chlorine, 10%
- 1.2 quarts
- Chart dose for 1 ppm in 10,000 gallons
- 12.84 fl oz
Cal hypo shock
Pool volume: 20,000 · What to do: Raise free chlorine · Product: Cal hypo, 67% · Reading now: 0 ppm · Target: 10 ppm
- Cal hypo, 67%
- 2.5 lb
- Chart dose for 1 ppm in 10,000 gallons
- 2.00 oz
Low alkalinity
Pool volume: 15,000 · What to do: Raise total alkalinity · Reading now: 60 ppm · Target: 100 ppm
- Sodium bicarbonate (baking soda)
- 8.4 lb
- Chart dose for 10 ppm in 10,000 gallons
- 1.40 lb
High alkalinity
Pool volume: 18,000 · What to do: Lower total alkalinity · Product: Muriatic acid, 31.45% · Reading now: 170 ppm · Target: 120 ppm
- Muriatic acid, 31.45%
- 1.83 US gallons
- Chart dose for 10 ppm in 10,000 gallons
- 26.00 fl oz
Stabilizer for a new season
Pool volume: 15,000 · What to do: Raise stabilizer (cyanuric acid) · Reading now: 0 ppm · Target: 40 ppm
- Cyanuric acid (stabilizer)
- 4.9 lb
- Chart dose for 10 ppm in 10,000 gallons
- 13.00 oz
How the doses are worked out
State dosage charts list how much of each product changes 10,000 gallons by one ppm of chlorine, or by ten ppm of alkalinity, hardness or stabilizer. Divide your gallons by that, multiply by the chart amount and by the change you need, and you have the dose.
For example, the chart puts 10.7 fl oz of liquid chlorine, 12%, or 2 oz of cal hypo, 67%, against one ppm of chlorine, and 1.4 lb of baking soda against ten ppm of alkalinity. Weaker or stronger liquid chlorine is scaled by its strength.
Target ranges
- Free chlorine: at least 1 ppm, or 2 ppm in a pool with stabilizer (CDC); 1 to 3 ppm is a common ideal.
- pH: 7 to 7.8, ideally 7.4 to 7.6.
- Total alkalinity: 60 to 180 ppm; with hypochlorite chlorine, 80 to 100 ppm is ideal.
- Calcium hardness: 200 to 400 ppm.
- Stabilizer (cyanuric acid): ideally 30 to 50 ppm, and no more than 90 ppm: the more stabilizer, the more chlorine it takes to do the same job.
Handle pool chemicals safely
- Add the chemical to water, never water to the chemical: it can react violently.
- Never mix products, not even two kinds of chlorine. Chlorine and acid together give off toxic chlorine gas.
- Add one product at a time with the pump running and nobody in the pool, then circulate and retest before adding more.
- Store chlorine and acids apart, dry, closed and out of reach.
Common questions
How much chlorine do I add to my pool?
For liquid chlorine, 12%, about 10.7 fl oz per ten thousand gallons for each ppm you want to raise free chlorine. The calculator scales it to your gallons, your product and the change you need.
How much baking soda raises alkalinity?
About 1.4 lb per ten thousand gallons raises total alkalinity by ten ppm.
How much muriatic acid lowers alkalinity?
About 26 fl oz of muriatic acid, 31.45%, per ten thousand gallons lowers total alkalinity by ten ppm. It lowers pH too, so retest both.
How much stabilizer do I need?
About 13 oz of cyanuric acid per ten thousand gallons raises it ten ppm. Aim for 30 to 50 ppm, and remember that trichlor tablets and dichlor add stabilizer as they dissolve.
Can I add chlorine and shock at the same time?
No. Never mix pool chemicals, and add one product at a time with the pump running. Let it circulate and retest before you add another.