How do you calculate a chemical feed pump setting?

Divide the required dose by the feed solution concentration, then multiply by the treated water flow in L/min. For a 2 mg/L dose, 100 mg/mL feed, and 227 L/min flow: 2 / 100 x 227 = 4.54 mL/min.

How do I convert gpm to L/min for the flow input?

Multiply gallons per minute by 3.785. So 60 gpm is about 227 L/min. Use the treated water flow past the injection point, not the pool turnover rate.

How do I get feed solution concentration in mg/mL?

Convert the product percent strength: 10% sodium hypochlorite is 100 mg/mL and 12.5% is 125 mg/mL. Multiply the percent by 10 to get mg/mL for water-based solutions.

Why is the pump output so small?

Because you are metering a concentrated solution into a large water flow. Here 4.54 mL/min of 100 mg/mL feed doses 227 L/min, only about 0.02 mL of concentrate per liter of water, a raw ratio of 0.02.

What if my feed solution is stronger than 100 mg/mL?

A stronger feed means less pump output for the same dose. Enter the higher mg/mL and the required mL/min drops proportionally, 125 mg/mL feed needs less than 100 mg/mL feed to hold the same 2 mg/L target.

Should I confirm the dose after setting the pump?

Always. Run the pump at the calculated setting, then test the residual downstream after the system stabilizes and fine-tune, since real feed strength and flow vary from the assumptions.

Pool, Spa & Water Treatment Chemistry calculator

Chemical Feed Pump Setting Calculator

A chemical feed pump setting is the mL per minute a metering pump must deliver to hit a target dose in a flowing water stream. Water treatment operators dialing in a chlorine or acid feed use it to translate a mg/L dose target into a physical pump output. Set it too high and you waste chemical and overshoot residual; too low and you fail to hold a disinfection setpoint. Because the pump meters concentrated solution into a much larger water flow, the numbers are small and precise, a fraction of a percent of flow, so the calculation removes the guesswork from tuning a feed system.

What this calculator does

Estimate chemical feed pump setting from required dose, flow, stock strength, and pump efficiency.
Use it to set metering pumps for sanitizer, acid, caustic, coagulant, or specialty treatment feeds.
It computes the metering pump output in mL/min needed to deliver a target dose into a given treated-water flow using a feed solution of known concentration.

Formula used

Feed pump setting = required dose / feed solution concentration x treated water flow in L/min

Inputs explained

Required treatment dose: Use the target applied dose for the treatment point.
Feed solution concentration: Convert product strength to active mg per mL. 10% sodium hypochlorite is 100 mg/mL. 12.5% is 125 mg/mL.
Treated water flow: Multiply flow in gpm by 3.785 to convert to liters per minute. For 60 gpm, enter 227.

How to use the result

Use it when commissioning or retuning a chemical feed pump, or after changing dose target, feed strength, or water flow.
It assumes a steady water flow and a stable feed solution strength; degraded chlorine or a fluctuating flow will drift the actual dose, so confirm with a residual test.

Current U.S. benchmarks

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Common questions

How do you calculate a chemical feed pump setting? Divide the required dose by the feed solution concentration, then multiply by the treated water flow in L/min. For a 2 mg/L dose, 100 mg/mL feed, and 227 L/min flow: 2 / 100 x 227 = 4.54 mL/min.
How do I convert gpm to L/min for the flow input? Multiply gallons per minute by 3.785. So 60 gpm is about 227 L/min. Use the treated water flow past the injection point, not the pool turnover rate.
How do I get feed solution concentration in mg/mL? Convert the product percent strength: 10% sodium hypochlorite is 100 mg/mL and 12.5% is 125 mg/mL. Multiply the percent by 10 to get mg/mL for water-based solutions.
Why is the pump output so small? Because you are metering a concentrated solution into a large water flow. Here 4.54 mL/min of 100 mg/mL feed doses 227 L/min, only about 0.02 mL of concentrate per liter of water, a raw ratio of 0.02.
What if my feed solution is stronger than 100 mg/mL? A stronger feed means less pump output for the same dose. Enter the higher mg/mL and the required mL/min drops proportionally, 125 mg/mL feed needs less than 100 mg/mL feed to hold the same 2 mg/L target.

Last reviewed 2026-05-12.