Cyanuric Acid
A chemical stabilizer that protects chlorine from UV degradation in outdoor pools.
Definition
Cyanuric acid (CYA) — also called stabilizer or conditioner — binds to free chlorine to protect it from UV photolysis. Without CYA, outdoor pool chlorine can degrade to near-zero within 30–60 minutes in direct sunlight. However, CYA also reduces chlorine's activity. As CYA increases, the minimum effective free chlorine level must increase proportionally. CYA above 80–100 ppm causes chlorine lock, where chlorine is present but largely ineffective. CYA cannot be reduced chemically — only dilution by partial drain and refill removes it.
Quick Facts
- Ideal Range
- 30–50 ppm
- Units
- ppm
- Also Known As
- CYA, cyanuric acid, stabilizer, conditioner, isocyanuric acid, chlorine stabilizer, pool conditioner
Relationships
Outgoing Relationships
- affected by → Water Replacement
- measured by → Water Testing
- calculated by → formula-07
- explained by → glossary/cyanuric-acid
- recommended for → Outdoor Pool
- related to → Free Chlorine
- uses → Stabilizer / CYA Granules
- uses → Trichlor Tablets
Incoming Relationships
- affected by ← Free Chlorine
- related to ← Water Replacement
- related to ← Automatic Chlorinator
- requires ← Outdoor Pool