Pool Stabilizer (Cyanuric Acid) Calculator: How Much to Add or Drain
How much stabilizer (cyanuric acid, CYA) raises your pool to a target level, or how much water to drain and refill to lower it.
Formula
Raise: stabilizer (oz) = (target − current) ÷ 10 × gallons ÷ 10,000 × 13. Lower (dilution): share to drain = (current − target) ÷ (current − fill water); gallons = share × pool volume.
Worked example
Inputs: Pool volume = 15000 gal; Current cyanuric acid (test result) = 0 ppm; Target cyanuric acid (from your pool builder or test kit guide) = 40 ppm; Cyanuric acid in your fill water = 0 ppm.
| Change ppm | 40 |
|---|---|
| Stabilizer oz | 78 |
| Stabilizer lb | 4.88 |
| Drain pct | — |
| Gallons to drain | — |
Follow the product label for how to add stabilizer, then circulate and retest. Liquid stabilizers are dosed differently: use their label.
FAQ
How much stabilizer per 10,000 gallons?
13 oz of cyanuric acid raises 10,000 gallons by 10 ppm. That is consistent with the math: 10 ppm of 10,000 gallons (about 83,400 lb of water) is 0.83 lb, or about 13.3 oz.
How much stabilizer for a 15,000 gallon pool?
From 0 to 40 ppm: 40 ÷ 10 × 1.5 × 13 = 78 oz, about 4.9 lb.
How do I lower stabilizer?
Only by draining part of the water and refilling with fresh water; no chemical removes it. Going from 100 to 60 ppm with CYA-free fill water means replacing 40% of the water (8,000 gallons of a 20,000 gallon pool).
Does chlorine add stabilizer?
Dichlor and trichlor are stabilized chlorine, so they add cyanuric acid over time; liquid chlorine and calcium hypochlorite do not. Test regularly if you use tabs.
Does this work for liquid stabilizer?
The 13 oz figure is for cyanuric acid itself. Liquid and blended products have different strengths, so use their label dose.
Sources
Related
- Pool Liquid Chlorine Calculator (Ounces to Raise Free Chlorine)
- Pool Salt Calculator (Pounds of Salt for a Saltwater Pool)
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Last reviewed 2026-10-20.