CYA / Stabilizer Calculator
Calculate how much cyanuric acid (stabilizer) to add to protect your chlorine from the sun.
CYA CALC
CYA / Stabilizer Adjustment
Quick-pick — auto-fills volume below.
0 if new pool or recently drained
Recommended: 30-50 ppm for regular pools
Stabilizer (CYA) Dosage
-- oz
Stabilizer to add
Also equals
-- lbs
Will raise CYA to
-- ppm
Buy Pool Stabilizer on Amazon
How to Add Stabilizer:
- Put stabilizer in a sock or pantyhose
- Hang in front of a return jet OR place in skimmer basket
- Squeeze periodically to help dissolve
- Takes 3-7 days to fully dissolve and show on test
What is CYA (Cyanuric Acid)?
CYA (also called stabilizer or conditioner) protects your chlorine from being destroyed by UV sunlight. Without CYA, you can lose 90% of your chlorine in just 2 hours of direct sunlight!
Target CYA Levels
| Pool Type | Target CYA |
|---|---|
| Regular Chlorine Pool | 30-50 ppm |
| Salt Water Generator (SWG) | 70-80 ppm |
| Indoor Pool | 0-20 ppm (optional) |
Warning - CYA is Quasi-Permanent!
CYA degrades very slowly (only about 3% per month on average), so the practical ways to lower it are to drain and refill with fresh water or use a professional reverse osmosis service. Don't use stabilized chlorine (trichlor pucks) if your CYA is already high.
CYA degrades very slowly (only about 3% per month on average), so the practical ways to lower it are to drain and refill with fresh water or use a professional reverse osmosis service. Don't use stabilized chlorine (trichlor pucks) if your CYA is already high.
CYA Too High?
High CYA reduces chlorine effectiveness. If your CYA is above 100 ppm, your chlorine is nearly useless!
How CYA Gets Too High
- Trichlor pucks/tablets - These contain 50% CYA and add ~3 ppm per week
- Dichlor granules - Also contain stabilizer
- Over-adding stabilizer - Easy to do if you don't test first
How to Lower CYA
- Drain and refill - Most reliable method (professional reverse osmosis also works)
- Drain 1/3 of pool = reduces CYA by ~1/3
- Consider switching to liquid chlorine (no CYA) for daily chlorine
For educational purposes only — full disclaimer ↓