Pool Stabilizer (CYA) Calculator
Without stabilizer, sunlight burns off chlorine in hours. Enter your pool size and reading to see how much to add.
Updated November 2026
How Much Stabilizer Does a Pool Need?
About 13 ounces (0.8 pound) of stabilizer per 10,000 gallons raises cyanuric acid by 10 ppm. A 15,000 gallon pool going from 0 to 40 ppm needs about 4.8 pounds.
Stabilizer dissolves slowly and only leaves the pool when water is drained. Add less than you think you need, wait a week and retest before adding more.
Pool Stabilizer Dosing Chart
Stabilizer (cyanuric acid) needed by pool size and how far you are raising CYA:
| Raise CYA by | 10k gal | 15k gal | 20k gal | 25k gal | 30k gal |
|---|---|---|---|---|---|
| 10 ppm | 13 oz | 1.2 lbs | 1.6 lbs | 2 lbs | 2.4 lbs |
| 20 ppm | 1.6 lbs | 2.4 lbs | 3.2 lbs | 4 lbs | 4.8 lbs |
| 30 ppm | 2.4 lbs | 3.6 lbs | 4.8 lbs | 6 lbs | 7.2 lbs |
| 40 ppm | 3.2 lbs | 4.8 lbs | 6.4 lbs | 8 lbs | 9.6 lbs |
| 50 ppm | 4 lbs | 6 lbs | 8 lbs | 10 lbs | 12 lbs |
Based on 0.8 lb per 10,000 gallons for each 10 ppm. Aim low. Overshooting can only be fixed by replacing water.
What should my stabilizer level be?
| Pool type | Target CYA |
|---|---|
| Outdoor pool with liquid chlorine, bleach or cal-hypo | 30 to 50 ppm |
| Outdoor salt water pool | The range in your salt system manual. Makers differ: 30 to 50 ppm for some systems, up to 60 to 80 ppm for others |
| Outdoor pool on chlorine tablets | 30 to 50 ppm, and test often because tablets keep adding it |
| Indoor pool | 0 ppm |
Higher stabilizer protects chlorine from the sun but also makes it work more slowly, so the chlorine level has to rise with it.
How do I add stabilizer?
- Test CYA and know your pool volume. The volume calculator helps if you are unsure.
- Put the stabilizer granules in a sock or mesh bag and tie it off.
- Hang the sock in front of a return jet or set it in the skimmer basket with the pump running.
- Squeeze it now and then to help it dissolve. It can take a day or two.
- Do not backwash or clean the filter for a week, and wait that long before retesting.
What if stabilizer is too high?
Above about 80 to 100 ppm, chlorine is held so tightly that it struggles to kill algae, a problem often called chlorine lock. No chemical removes stabilizer reliably. The fix is to drain part of the water and refill.
The chlorine lock drain calculator works out how much water to replace.
The usual cause is chlorine tablets and stabilized shock. Each 10 ppm of chlorine added by trichlor tablets also adds about 6 ppm of stabilizer, and dichlor adds about 9 ppm. Over a season that builds up.
Frequently Asked Questions
How much stabilizer for a 10,000 gallon pool?
About 13 ounces raises a 10,000 gallon pool by 10 ppm. To go from 0 to 40 ppm, add about 3.2 pounds.
Are stabilizer, conditioner and cyanuric acid the same thing?
Yes. Pool stabilizer, pool conditioner and cyanuric acid, often shortened to CYA, are all the same chemical.
How long does stabilizer take to work?
It starts protecting chlorine as it dissolves, but a test may not show the full reading for up to a week.
Do I need to add stabilizer every year?
Only what was lost. Stabilizer does not get used up. It drops when water is splashed out, backwashed or drained, so test in spring and top up to your target.
How long after adding stabilizer can I swim?
About 20 minutes, as long as no undissolved granules are on the pool floor.
Sources
- Hayward: AquaRite owner's manual, water chemistry and saturation index
- Pentair: IntelliChlor installation and user's guide
- CDC: Home pool and hot tub water treatment and testing
Stabilizer set? Now set chlorine
Your chlorine target depends on your stabilizer level. Get the daily dose for your pool.
Related: Shock calculator · Dosage calculator · How to test pool water