Cyanuric Acid (Stabilizer) Calculator

Raise uses the operator mass-balance rule: granular stabilizer scales with pool volume and the ppm you want to add. The field-standard high-purity rule is 13 oz raises 10 ppm in 10,000 gallons (the headline); the 1-lb-bag rule is the band's high end.

deltaCya = target − current        (raise needs deltaCya > 0)

granular (high-purity, headline):  oz = 0.00013 × gallons × deltaCya
granular (1-lb-bag, band high):    oz = 0.00016 × gallons × deltaCya
liquid / instant (32–35%):     fl oz = 0.0004  × gallons × deltaCya

Lower (drain & dilute — no chemical lowers CYA):
  drainFraction = (current − target) / (current − fillWaterCya)
  gallons to replace = drainFraction × pool gallons
  resulting CYA      = current × (1 − f) + fillWaterCya × f   (= target)

The two published granular rules disagree by about 23% (0.00016 / 0.00013 ≈ 1.23) because granular-CYA purity varies, so we present a band, not a single false-precision number. Liquid stabilizer has one published rule, so no band applies.

Dichlor isn't a dosing path. Chlorinating with dichlor or trichlor raises CYA as a side-effect (about +0.9 ppm CYA per 1 ppm of free chlorine) — it's usually why CYA is already too high, so selecting it shows a warning, not a dose. To add CYA on purpose, use granular or liquid stabilizer.

No chemical lowers cyanuric acid. The only lever is replacing water with fresh fill — we compute the drain percentage and the gallons to replace. With a non-zero fill-water CYA the general dilution identity applies. Drain to waste per your local rules.

Sources: PoolDial — Cyanuric Acid Calculator (the 0.00013 closed form + dilution example); Benchmark Pool Supply (1-lb-bag and liquid rules); Test Your Own Pool (CYA only comes down by draining and refilling); Pool Research (the dual-mode framing). These are calculator-hub / retailer pages — treat the exact constants as approximate, which is why the granular dose is shown as a band.