How the pool stabilizer (cya) calculator works
Stabilizer binds to chlorine and shields it from UV. With none in the water, a sunny afternoon can strip most of your free chlorine before dinner.
CYA does not burn off or evaporate. The only way down is draining water and refilling, so the calculator stops you from overshooting.
The formula, step by step
Pounds = (Target CYA - Current CYA) x Gallons x 8.34 / 1,000,000
- Subtract your current CYA from the target.
- Multiply the gap by your gallons.
- Multiply by 8.34 pounds per gallon of water.
- Divide by one million to get pounds of stabilizer.
Worked example
A 15,000 gallon pool reads 10 ppm CYA and you want 40 ppm.
Gap = 30 ppm. 30 x 15,000 x 8.34 = 3,753,000.
Divide by 1,000,000 and you get 3.75 pounds of stabilizer.
Watch it done
This short video walks through the same job in real life, so you can match what you see on screen to what you do at the pool.
Tips before you start
Granular stabilizer takes days to dissolve. Put it in a sock hung in the skimmer, squeeze it twice a day, and do not backwash for a week.
Every trichlor tab adds CYA. If you dose tabs all summer and never drain, your CYA climbs until chlorine stops working, which owners often mistake for a bad batch of chlorine.
Pool Stabilizer (CYA) Calculator FAQs
What should pool stabilizer be?
30 to 50 ppm for a chlorine pool and 60 to 80 ppm for a salt pool. Indoor pools do not need any.
How do I lower cyanuric acid?
Drain part of the pool and refill with fresh water. Draining a quarter of the water cuts CYA by about a quarter.
Can I have too much stabilizer?
Yes. Above 100 ppm chlorine gets locked up and the water can go cloudy or green even with a normal test reading.