Once you know your pool volume, dosage math is just ratios. The formula below works for every chemical you add — chlorine, acid, soda ash, CYA, calcium. Memorize it and you can dose any pool of any size on the fly.
The universal dosing formula
Dose needed = (Desired ppm change × Pool volume in 10,000-gal units) × Chemical dose factor
Chemical dose factors (oz or lbs needed to raise 10,000 gal by 1 ppm of the target parameter):
| Target | Chemical (strength) | Dose factor per 10,000 gal / 1 ppm |
|---|---|---|
| +1 ppm free chlorine | Liquid hypo (12.5%) | ~10.6 fl oz |
| +1 ppm free chlorine | Cal-hypo (65%) | ~2.0 oz (weight) |
| +1 ppm free chlorine | Trichlor (90%) | ~1.5 oz (weight; +0.9 ppm CYA) |
| +10 ppm CYA | Granular cyanuric acid | ~13 oz (0.83 lb) |
| +10 ppm calcium hardness | Calcium chloride (77%) | ~1.5 lb |
| +10 ppm total alkalinity | Sodium bicarbonate | ~1.4 lb |
| -0.2 pH | Muriatic acid (31.45%) | ~8 fl oz |
| +0.2 pH | Soda ash | ~6 oz |
Why percent available chlorine matters
“Chlorine” isn't one product — it's a category. Each product has a different percent available chlorine(often written “% avail Cl”):
- Liquid hypo (sodium hypochlorite): 10–12.5% (homeowner / pool-service grade)
- Cal-hypo (calcium hypochlorite): 65–73% granular
- Trichlor: 90% (tablets/sticks; yields ~55% CYA by mass)
- Dichlor: 56–62% (granular; also contains ~50% CYA)
Higher percent = less product per ppm — but also more of whatever comes with it (CYA for trichlor/dichlor, calcium for cal-hypo). Pick the chemical that matches what your pool needs to avoid, not just the cheapest per ppm.
Worked example: dosing chlorine
Pool: 19,150 gallons, free chlorine currently 0.5 ppm, target 3 ppm.
Change needed: +2.5 ppm
Product: liquid hypo 12.5%
Dose factor: 10.6 fl oz per 10,000 gal per ppm
Dose: 2.5 × (19,150 ÷ 10,000) × 10.6 = 2.5 × 1.915 × 10.6 = ~50.7 fl oz
That's ~1.6 quarts of 12.5% liquid chlorine. Cross-check on a calculator before dumping anything.
Worked example: dosing acid
Pool: 19,150 gallons, pH 7.8, target 7.4.
Change needed: −0.4 pH (i.e., two “-0.2 doses”)
Product: muriatic acid 31.45%
Dose factor: 8 oz per 10,000 gal per 0.2 pH drop
Dose: 2 × (19,150 ÷ 10,000) × 8 = 2 × 1.915 × 8 = ~30 fl oz
But: start with half-dose, retest after 4 hours, dose again if needed. Never go all at once.
The golden rules of dosing
- Never dose twice in a row. Wait 4 hours, retest, then re-dose.
- Always dose with the pump running so the chemical disperses.
- Pre-dissolve dry chemicals in a bucket of pool water before broadcasting.
- Add acid to water, never water to acid. Splash protection.
- Check the label for the actual strength — concentrations vary by manufacturer.
Want a pro to handle this?
Our CPO-certified techs run this exact playbook on every weekly service visit.