Which unit is commonly used to express the chlorinator output rate for chemical feeders?

• A. lb/day
• B. mg/L
• C. gpm
• D. mg/min

Answer: (A)

When dosing chemicals for chlorination, the feed rate is expressed as the amount of chlorine added over a period of time, so you’re thinking in terms of mass per day. Pounds per day is the standard unit because it directly reflects how much chlorine is being introduced into the system each day, which aligns with daily demand, reporting, and inventory tracking. Concentrations like mg/L describe how much chlorine is present in a given volume of water, not how much the feeder is delivering over time. A flow rate like gpm measures water movement, not the chemical dose. While mg/min could be used in some specific contexts, the conventional and most practical expression for a chlorinator’s output is pounds per day.