Cyanuric Acid Calculator

Calculate how much stabilizer to add — or how much water to drain — to reach your target CYA level.

Saltwater Pool Off

Pool Volume

gal

Current CYA Level

ppm

Target CYA Level

ppm

Recommended: 30–50 ppm (freshwater) · 70–80 ppm (saltwater)

Raise CYA — Add Stabilizer

Stabilizer Needed

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CYA Increase

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Chlorine Lock Risk Your target CYA is above 80 ppm. At high CYA levels, chlorine becomes less effective — this is called "chlorine lock." Ideal range is 30–50 ppm for freshwater and 70–80 ppm for saltwater pools.

CYA Too High Current CYA is above 100 ppm. The only way to lower CYA is to drain and refill part of the pool. There is no chemical that removes CYA.

Safety Notes Add stabilizer (cyanuric acid) directly to the skimmer slowly, or pre-dissolve in a bucket of warm water. Never add directly to the pool while the pump is off. Results take 24–48 hours to stabilize. Do not add other chemicals for 24 hours after adding stabilizer.

About Cyanuric Acid (Pool Stabilizer)

Cyanuric acid (CYA), also called pool stabilizer or conditioner, protects chlorine from being broken down by UV sunlight. Without it, the sun can destroy up to 90% of your pool's chlorine within 2 hours.

Ideal range: 30–50 ppm for freshwater pools. 70–80 ppm for saltwater pools (since salt chlorinators produce chlorine continuously). Above 80 ppm, chlorine effectiveness drops significantly. Above 100 ppm, you must drain and dilute.

Formula used: 13 oz of granular stabilizer per 10,000 gallons raises CYA by approximately 10 ppm. To lower CYA, partial drain-and-refill is the only option: drain % = (current − target) / current.

Note: Trichlor tablets and dichlor shock both contain CYA. If you use them regularly, your CYA level will gradually rise over the season without adding standalone stabilizer.