Free tool
Cyanuric Acid (Stabilizer) Calculator
Stabilizer to raise cyanuric acid, an honest drain-and-refill calculation to lower it — no fabricated dosing math.
How to use this calculator
- 1Enter your pool volume
Don't know it? Use the Pool Volume Calculator first — this tool is built to work with that gallon figure.
- 2Choose raise or lower CYA
Enter your current and target cyanuric acid readings from a test kit.
- 3Raising: dose it slowly
The calculator shows how much stabilizer to add — feed it through a skimmer feeder or a sock, since CYA dissolves slowly and shouldn't be broadcast.
- 4Lowering: read your drain-and-refill amount
There's no chemical that lowers CYA — the calculator instead shows how much water to drain and replace with fresh water to hit your target.
Frequently asked
Questions about cyanuric acid
Why does CYA need to be added slowly, through a feeder or sock?
Cyanuric acid dissolves much more slowly than most pool chemicals. Broadcasting it directly into the pool leaves undissolved granules sitting on the floor, which can bleach a vinyl liner and won't fully register on a test for several days. Feeding it through a skimmer feeder or a mesh sock hung in front of a return dissolves it gradually and evenly.
Why isn't there a chemical dose for lowering cyanuric acid?
Because there genuinely isn't one — CYA doesn't break down on its own and no chemical additive removes it from pool water. The only real fix is diluting it out with a partial drain-and-refill using fresh water.
What's the ideal cyanuric acid range?
Most pool professionals target 30-50 ppm, with 20-80 ppm considered acceptable. Too little lets sunlight burn off chlorine within hours; too much is widely associated with "chlorine lock," where chlorine becomes far less effective even at a normal ppm reading.
Does using stabilized chlorine (dichlor or trichlor) affect this?
Yes — dichlor and trichlor add cyanuric acid with every dose, so pools that use them as their primary chlorine source tend to creep upward in CYA over time even without ever adding stabilizer directly. That's often the real reason a drain-and-refill becomes necessary.