Cyanuric Acid
Cyanuric acid is a stabilizing compound that forms a reversible bond with free chlorine in pool water, protecting it from UV degradation.
Definition
Cyanuric acid is a stabilizing compound that forms a reversible bond with free chlorine in pool water, protecting it from UV degradation.
Typical Values: Standard pools: 30–50 ppm; Salt pools: 60–80 ppm; Never above 100 ppm for normal pools
In Plain Language
Without CYA, free chlorine in an outdoor pool is destroyed by direct sunlight within 2–3 hours. CYA forms a temporary bond with chlorine molecules, slowing UV breakdown. However, CYA also moderately reduces chlorine's sanitising speed. Above 80 ppm, the effect becomes significant enough that normal chlorine doses provide inadequate sanitisation.
Why It Matters
CYA is essential for outdoor pools using chlorine, but must be kept below 80 ppm. It cannot be reduced except by dilution (partial drain).
Typical Values
Standard pools: 30–50 ppm; Salt pools: 60–80 ppm; Never above 100 ppm for normal pools
Last reviewed: 2026-06-01