Pond Pump Size Calculator – What Pump for My Pond

Use the free Pond Pump Size Calculator below, right in your browser. No sign-up, no software to install, and nothing is sent to a server.

A pond pump is the heart of the system: it drives water through the filter, feeds the waterfall, and keeps the whole pond moving. A pump that is too small leaves stagnant corners and a filter that barely works, while a pump that is far too large wastes electricity and can scour plants and stress fish. This calculator sizes the pump from pond volume and lift height.

Enter your pond volume in litres and the height the water must be lifted, in metres, from the pond surface to the top of the waterfall or filter inlet. The tool targets a turnover of about one point two times the pond volume per hour, then adds twelve percent for each metre of lift. The result is the flow you should look for on the pump curve at your real head height.

Turnover is simply how often the pump moves the whole pond volume. Once per hour is a common target for a lightly stocked pond, and one point two times gives a margin for pipe losses and filter resistance. Heavily stocked koi ponds often aim higher, near twice per hour, so if your pond is heavily stocked, treat this result as a minimum and consider the next pump size up.

Head height is the vertical distance the pump must lift water, and it is the figure most often underestimated. Measure from the pond surface to the highest point the water reaches, not to the pump itself or to the middle of the waterfall. A waterfall that looks modest can still lift water a full metre, and that metre costs a large share of a small pump output. Always read the pump curve at your head height.

Pipe losses add to head height in practice. Long runs, narrow hose and tight bends all slow the flow, and a dirty filter adds resistance too. This calculator includes a margin for lift, but it cannot see your pipe layout. If your run is long or narrow, choose a pump one size up, use the widest hose the pump accepts, and keep bends gentle. A short wide pipe run is worth more than a bigger pump on a long thin hose.

Waterfall width also shapes the choice. A thin trickle over a wide fall looks wrong, while a narrow fall can look dramatic with modest flow. As a rough guide, a waterfall about thirty centimetres wide wants roughly two thousand to three thousand litres per hour for a pleasant sheet of water. If your fall is wide, size the pump for the look you want as well as for filtration, and use a separate smaller pump for the filter if one pump cannot do both jobs well.

Energy cost is a real part of pump choice, because the pump runs all day and often all year. A pump that draws twenty watts more than needed costs real money over twelve months of continuous running. Compare watts at your head height, not just headline flow, and consider a variable speed pump if your budget allows: it lets you turn the flow down in winter and up in summer without swapping hardware.

Place the pump where it can be reached for cleaning, and protect the intake with a cage or pre-filter so leaves and fry are not sucked in. A pump buried under silt or wrapped in blanket weed will overheat and fail early, and a pump that runs dry for even a short time can be destroyed. Check the intake weekly in autumn when leaves fall, and keep a spare impeller if your maker sells one.

Winter running needs a decision, not an accident. In mild climates many ponds run all year, which keeps oxygen up and the filter alive. In hard frost, a running waterfall can chill the pond and build ice dams that divert water out of the pond. If you switch the pump off for winter, keep a small air pump or heater running to hold an ice-free hole for gas exchange, and restart the filter gradually in spring.

Finally, test the installed pump rather than trusting the box. Time how long it takes to fill a known container at the waterfall, or watch the filter outlet flow over a week. If the flow is clearly below the calculated figure, check for a clogged intake, a kinked hose or a dirty filter before blaming the pump. Most disappointing pump performance traces back to the pipework around it, not to the pump itself.

Versión en español: Tamaño de bomba para estanque – Caudal según altura