Cyanuric acid (CYA) calculator
Cyanuric acid is sunscreen for your chlorine. Enter your current and target CYA and pool volume to get the exact amount of stabilizer to add.
How much stabilizer to add?
About 13 oz of cyanuric acid per 10,000 gallons raises CYA by roughly 10 ppm. The calculator scales it to your volume. Add it via the skimmer sock or feeder — it dissolves slowly, so don’t backwash for 48 hours and re-test in about a week before adding more.
Why CYA matters
Without stabilizer, sunlight destroys free chlorine within hours. With it, chlorine lasts. But too much CYA weakens chlorine’s sanitizing power, which is why your free-chlorine target rises with your CYA (about 7.5% of CYA).
CYA too high?
There’s no chemical that removes CYA — the only fix is dilution. The calculator shows the percentage of water to replace to reach your target. Going forward, use liquid chlorine or cal-hypo (no added CYA) to stop it creeping up.
Ideal ranges
| Level | Target | Notes |
|---|---|---|
| Chlorine pool | 30–50 ppm | |
| Saltwater pool | 60–80 ppm | Protects chlorine from sun |
| Hot tub / spa | 20–40 ppm |
Frequently asked questions
Is CYA the same as conditioner or stabilizer?
Yes — cyanuric acid, stabilizer, and conditioner are the same thing.
Why is my chlorine demand so high?
Very high CYA can make chlorine feel ineffective (“chlorine lock”). Confirm the reading and dilute to bring CYA into range.
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