5 Things to Know About Pool Cyanuric Acid Levels

Keep CYA between 30 and 50 ppm This range protects chlorine from sunlight without making it ineffective.

CYA acts as sunscreen for chlorine Sunlight destroys free chlorine quickly—half can be gone in an hour on a clear day without it.

Above 50 ppm, chlorine gets lazy High CYA binds chlorine, making it less effective at killing algae and bacteria. You’ll need more chlorine to compensate.

Below 30 ppm, you lose too much chlorine to the sun You’ll waste money and chemicals trying to keep the pool sanitized.

Test monthly and adjust as needed For pools in full sun, aim for 45–50 ppm. Use stabilizer to raise CYA or partial drain to lower it.