The headline flow is normally the pump’s best-case output. Installed flow is the point where the pump curve meets the resistance created by your system.
Start with static head
Measure vertically from the pond’s operating water level to the highest discharge point—not along the hose. Hose length matters through friction; vertical rise determines static head.
A maximum-head figure is not an operating point
At maximum head, flow has normally fallen to zero. Use the complete manufacturer performance curve.
Then allow for friction
- Use the widest sensible hose supported by pump and filter.
- Keep runs direct and avoid unnecessary tight elbows.
- Clean cages and media before diagnosing a weak pump.
- Use component loss data where the manufacturer provides it.
Read the pump curve
Target flow at total installed head ≤ delivered flow shown by the curve
A linear estimate can screen candidates when data is limited, but it should be labelled as an estimate. Continue with the hose guide.