Calculators / Chlorine Dose and Feed
Chlorine Dose and Feed calculator
Dose is demand plus the residual you want left over. Feed rate is the pounds formula applied to the dose. With hypochlorite, divide by the percent available chlorine.
Dose (mg/L) = Demand + Residual Feed (lbs/day) = Flow MGD × Dose × 8.34 ÷ (% available ÷ 100)
Worked example
A plant treats 4 MGD. Chlorine demand is 5.5 mg/L and you want a 0.5 mg/L residual. How many lbs/day of 65% calcium hypochlorite do you need?
- Dose = 5.5 + 0.5 = 6 mg/L
- Pure chlorine = 4 × 6 × 8.34 = 200.16 lbs/day
- Product = 200.16 ÷ 0.65 = 307.94 lbs/day
Answer: 307.94 lbs/day
Common mistakes
- Forgetting to add the residual to the demand.
- Multiplying by the percent instead of dividing.
Check your exam's reference sheet for its exact constants. Some use 3.14 instead of 3.1416, which changes answers in the last digit.