Cyanuric Acid (CYA) Calculator
Cyanuric acid — also called stabilizer or conditioner — protects chlorine from being burned off by sunlight. Target range for outdoor pools: 30–50 ppm (saltwater pools: 60–80 ppm is common).
How the math works
- CYA (lbs) = (Target − Current) ppm × Gallons × 8.34 ÷ 1,000,000
- Example: raising a 12,000 gal pool from 0 to 40 ppm needs 40 × 12,000 × 8.34 ÷ 1,000,000 ≈ 4 lbs of stabilizer
Critical warnings before you add
- CYA is nearly impossible to remove — the only fixes are draining water or waiting months. Add less than you think, retest, repeat.
- Never backwash or overflow for 7 days after adding — stabilizer takes up to a week to fully dissolve.
- Do NOT put granular CYA in the skimmer — it can clog your filter and damage the plumbing. Dissolve it in a sock hung in front of a return jet, or use liquid stabilizer.
- Trichlor tablets add CYA continuously. If you use tablets all season, your CYA creeps up every week — test it monthly.
Frequently asked questions
How much stabilizer raises CYA by 10 ppm?
About 13 oz (0.83 lbs) per 10,000 gallons. For a full jug-sized treatment: a 15,000 gal pool needs roughly 1.25 lbs to move 10 ppm.
Do saltwater pools need stabilizer?
Yes — salt cells make chlorine just like bleach does, and sunlight destroys unstabilized chlorine at the same speed. Saltwater pools commonly run 60–80 ppm CYA so the cell isn't overworked.
My CYA is too high. How do I lower it?
Drain and refill part of the pool — there is no chemical that removes CYA. If you use trichlor tablets, switching to liquid chlorine stops the CYA from climbing further.