Pool Free-Chlorine Dose by Product
Free-chlorine dose = ppm x (gal/1e6) x 8.34 lb, divided by the product available-chlorine fraction.
Example
You enter
- Target free-chlorine rise (ppm) 2
- Pool volume (gallons) 15000
- Product cal-hypo-65
You get
- Chlorine mass 0.25
- Dry (oz) 6.2
Checked against published worked examples from: Whatcom County, WA.
Details, formula, and sources
Scopeas dry oz or (liquid) fl oz. A 15,000 gal pool +2 ppm needs 6.2 oz of 65% cal-hypo, or 30.7 fl oz of 12.5% liquid. The product label governs.
Formula or tablelb_cl = ppm x (gallons/1e6) x 8.34; lb_prod = lb_cl / (avail/100) for dry products; for liquid, lb_prod = liquid gallons x 8.34 x (1 + 0.0158 x trade %) (about 10 lb/gal at 12.5%); dry_oz = lb_prod x 16; liq_floz = lb_cl / (avail/100 x 8.34) x 128 (liquid sold by trade percent, grams of available chlorine per 100 mL).
Source and editionThe standard pool free-chlorine dose mass balance and product available-chlorine fractions, by name.
Free accessThe 8.34 lb/gal water constant and product available-chlorine strengths are published free by pool-care references and product labels. The product label directions govern.
What governsEstimate. AHJ and licensed professional govern.
API field namesppm, gallons, product, lb_cl, dry_oz
- Mass balance lb chlorine = ppm x (gal/1e6) x 8.34; dry product weight = /available fractionpool-care practice
- Product strengths liquid 12.5% trade, cal-hypo 65%, dichlor 56%, trichlor 90%; liquid volume = lb chlorine / (trade percent x 8.34) galproduct labels
- No demand/CYA does not subtract chlorine demand or model the CYA effectscope of this tile