How to use this pool stabilizer calculator
- Enter the pool volume.
- Test CYA (stabilizer).
- Enter the target: about 30–50 ppm for chlorine pools, 70–80 ppm for salt pools.
- Dissolve stabilizer slowly (in a sock in the skimmer or a bucket); it can take a week to fully register.
Example
A freshly filled 20,000 gallon pool needs 6.68 lb (106.8 oz) of stabilizer to reach 40 ppm of CYA.
What to know before you buy
What stabilizer does
Cyanuric acid (CYA) shields chlorine from the sun's UV rays, which can destroy unprotected chlorine in a few hours. Outdoor pools need stabilizer; indoor pools generally do not.
Why too much is a problem
The more CYA in the water, the higher the chlorine level needed to sanitize. At very high CYA, keeping enough active chlorine becomes impractical and the only fix is to partially drain and refill.
Stabilizer to raise CYA by 10 ppm
| Pool volume | Stabilizer to add | Pounds |
|---|---|---|
| 5,000 gal | 6.7 oz | 0.42 lb |
| 10,000 gal | 13.4 oz | 0.83 lb |
| 15,000 gal | 20 oz | 1.25 lb |
| 20,000 gal | 26.7 oz | 1.67 lb |
| 30,000 gal | 40.1 oz | 2.5 lb |
Formula
Stabilizer (g) = liters × ppm increase ÷ 1,000 (cyanuric acid is almost 100% pure). Drain fraction = 1 − target ÷ current.
Tips from the pros
- Trichlor tablets and dichlor add CYA every time you use them; track CYA monthly.
- Do not backwash for a few days after adding granular stabilizer.
- Aim for 30–50 ppm with liquid chlorine, 70–80 ppm for salt pools, per common guidance.
Common mistakes to avoid
- Adding more stabilizer because the reading has not risen after one day.
- Letting CYA climb above 90–100 ppm, which makes chlorine much less effective.
Frequently asked questions
How much stabilizer raises CYA by 10 ppm?
About 13 oz per 10,000 gallons.
Why is my CYA reading not going up?
Granular stabilizer dissolves slowly. Wait 5–7 days with the pump running before retesting.
How much stabilizer for a 20,000 gallon pool?
About 1.7 lb (26.7 oz) raises CYA by 10 ppm in 20,000 gallons.
Does stabilizer evaporate?
No. CYA only leaves with water that is splashed out, backwashed or drained, not through evaporation.