--- title: "Pond Pump Size Calculator: Flow & Head | Pond Mosaic" description: "What size pond pump do you need? Filter flow from your pond volume, the real flow at your head height from the pump chart, waterfall flow and running cost." url: https://pondmosaic.me/pond-pump-calculator/ --- Litres and gallons per hour # Pond pump calculator What size pump does a pond need? For a filtered fish pond, Hozelock suggests the whole volume through the filter every 1½ to 2½ hours, so a 3,600-litre pond needs **about 1,440 to 2,400 litres an hour at your head height**. Wildlife ponds need no pump at all. ## How to size a pond pump Work out the flow you need, then find a pump that gives it *at your head height*. The flow printed on the box is typically the most the pump will push, under a light load (Aquascape); every metre it has to lift water, through a filter or up to a waterfall, costs flow. Manufacturers print a chart of flow against head on the box or in the manual. - **Filter flow:** Hozelock suggests the whole pond through its filter every 1½–2½ hours, the faster end for koi; Blagdon says every 2–4 hours. Follow your own filter's rating where it differs. - **Head:** the height from the pond surface to the outlet, plus an allowance for the pipe. Bradshaws reckons horizontal pipe costs about a tenth as much as height. Narrow pipe and many bends cost more, so leave a margin. - **Waterfalls:** the two rules differ: Bradshaws allows 1,000 L/h per 10 cm of width, Aquascape 1,500 US gal/h per foot, nearly twice as much, for a fuller sheet. - **Running cost:** watts × hours ÷ 1,000 × the price per kWh. The default is Ofgem's average cap rate for Great Britain from 1 October to 31 December 2026, 26.32p per kWh; use your own tariff's unit rate. - **Wildlife ponds** need no filter; if you add a fountain, choose a pump with a wildlife guard. **Before you buy a pump, filter or liner at a surprising discount** from an unfamiliar shop you saw advertised on social media, it's worth a quick check. See how long the shop's domain has existed with WebTraceCheck's [DNS and domain lookup](https://webtracecheck.com/dns-lookup), and if you'd rather not open the link on your own device, open it in WebTraceCheck's [disposable cloud browser](https://webtracecheck.com/), which is deleted after each session. ## Sources 1. Hozelock, [Cyprio Ecopower+ filter instructions](https://manualslib.com/manual/1772999/Hozelock-Cyprio-Ecopower-4000.html?page=6), p. 6: pond volume through the filter every 1½–2½ hours, the fastest rate for koi; condition factors +25% for an average depth under 0.75 m, +25% for full sun, +0% / +15% / +35% by climate. 2. Blagdon, [Minipond filter FAQ](https://media.diy.com/is/content/KingfisherDigital/Marketplace/5015368010528_MNL_MP): pump the pond volume through the filter every 2–4 hours. 3. RHS, [Wildlife ponds](https://www.rhs.org.uk/ponds/wildlife-ponds): a wildlife pond doesn't need a filter; use a pump with a wildlife protection system. RHS, [Choosing a pond filter](https://www.rhs.org.uk/ponds/filters): ponds with few or no fish shouldn't require a filter. 4. Bradshaws, [Pump operating head](https://bradshawsdirect.co.uk/blog/pond-pumps-pump-operating-head) (21 November 2019): flow falls as head rises; horizontal distance reduces flow by about a tenth as much as height. [Waterfall flow rates](https://www.bradshawsdirect.co.uk/index.php/blog/waterfall-flow-rates): allow 1,000 L/h per 10 cm of width. 5. Aquascape, [Pond Builder's Bible, chapter 7: pumps and electrical](https://cdn.shopify.com/s/files/1/0710/7782/2767/files/Chapter-07.pdf): 1,500 gph of flow for each foot of spillway width; pumps deliver less than their rating as total dynamic head rises. 6. Ofgem, [Changes to energy price cap between 1 October and 31 December 2026](https://www.ofgem.gov.uk/news/changes-energy-price-cap-between-1-october-and-31-december-2026) (26 August 2026): electricity on average 26.32p per kWh on a Direct Debit default tariff, plus a 54.83p daily standing charge; no VAT on electricity from 1 October 2026 to 31 March 2027. As of 2 November 2026. 7. US EIA, [Electric Power Monthly, table 5.3](https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_3) (released 23 October 2026): average residential price 18.16 cents per kWh in August 2026 (preliminary). The running cost leaves out standing charges, which you pay whether the pump runs or not. The example pump chart is made up to show the method. ## Pond pump questions **What size pump do I need for my pond?** For a filtered fish pond, one that moves the whole volume through the filter every 1½–2½ hours at your head height (Hozelock). A 3,600-litre pond needs about 1,440–2,400 litres an hour. **What does head height mean on a pond pump?** The height the pump lifts water above the pond surface. The flow falls as the head rises, so read the flow at your head off the pump's chart, not the maximum on the box. **Does a wildlife pond need a pump?** No. The RHS says a wildlife pond doesn't need a filter. A pump is only for a fountain or cascade, and should have a wildlife guard. **How much does it cost to run a pond pump?** Watts × hours ÷ 1,000 gives kWh; multiply by your unit price. A 60 W pump running all day uses 1.44 kWh, about 38p a day at 26.32p per kWh.