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 for dichlor, +0.6 ppm for trichlor — and it's usually why CYA is already too high, so selecting it shows a warning, not a dose. The two products differ because each carries one cyanurate ring but trichlor releases three chlorines to dichlor's two. 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. The staged version of that drain, split into cycles when one pass would empty too much of the pool, is planned on the drain and dilution calculator, and the reason a number is too high or too low in the first place is the chlorine it demands, which the FC to CYA ratio calculator spells out. If tablets are your chlorine source, the sizing the tablet load itself shows how much stabilizer that habit adds over a season.

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.