PondTools

Pump turnover and head loss calculator

These numbers are typed in. Trace your pond once and every calculator uses its measured volume and depths.

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Required flow

Required flow
Not calculatedGPH

Head loss

Total dynamic head at that flow
Not calculatedft

Delivered flow

Flow you can expect
Not calculatedGPH
How it works

This assumes smooth pipe. Fittings, valves and corrugated tubing add losses that can cut the flow you actually get. Check the manufacturer’s performance chart.

required GPH = pond volume (gal) ÷ turnover time (hr) turnover time = 2 hr light/plant  ·  1 hr goldfish-type  ·  0.5 hr koi
total dynamic head = static lift + friction loss friction loss (ft per 100 ft of pipe) = 0.2083 × (100 / C)^1.852 × GPM^1.852 / diameter(in)^4.8655 C = 150 for smooth PVC, PE or vinyl pipe or tubing

The turnover rates are rules of thumb. Static lift is the height from the pond surface up to where the water comes out. Measure the whole pipe run, including any coils and slack. The flow to check starts at the required flow, and you can type a pump’s rated flow instead to see the head loss at that flow.

Head loss is worked out with Hazen-Williams at C = 150. For the delivered flow, we draw a straight line between your two chart points and find where it meets the head your plumbing needs. It won’t guess beyond those two points. Pick points far apart on the manufacturer’s chart, because the estimate is only as good as your reading of them.

Want the precise number?

Type your measurements in above for a quick estimate. For the real volume, trace your pond on a photo or satellite image and set its depths. PondTools measures the actual outline, so dosing, liner and pump sizes come out right.

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