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.
Suggested flow through the filter
900–2,400 L/h
238–634 US gal/h · 198–528 UK gal/h
- Pond
- 951 US gal · 792 UK gal (3,600 litres)
- Hozelock
- whole pond through the filter every 1½–2½ hours:
1,440–2,400 L/h (380–634 US gal/h) - Blagdon
- whole pond through the filter every 2–4 hours:
900–1,800 L/h (238–476 US gal/h)
This is the flow the pump must deliver at your head height, not the number on the box: read it off the pump's chart below.
Flow at your head height
2,670 L/h
705 US gal/h · 587 UK gal/h · 44.5 L/min
- Head to read
- 1.7 m (1.2 m lift + 0.5 m for 5 m of pipe)
- How
- Between 1 m (3,300 L/h) and 2 m (2,400 L/h), in a straight line
Waterfall or stream flow
3,000–5,589 L/h
793–1,476 US gal/h for a 30 cm (11.8 in) spillway
- Bradshaws
- 3,000 L/h (793 US gal/h, 660 UK gal/h)
1,000 L/h per 10 cm of width - Aquascape
- 5,589 L/h (1,476 US gal/h, 1,229 UK gal/h)
1,500 US gal/h per foot of width
Running cost
£138.34 a year
£11.53 a month · £0.38 a day
- Energy
- 1.44 kWh a day · 526 kWh a year
- Worked out as
- 60 W × 24 h ÷ 1,000 × 26.32p per kWh
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.
Sources
- Hozelock, Cyprio Ecopower+ filter instructions, 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.
- Blagdon, Minipond filter FAQ: pump the pond volume through the filter every 2–4 hours.
- RHS, Wildlife ponds: a wildlife pond doesn't need a filter; use a pump with a wildlife protection system. RHS, Choosing a pond filter: ponds with few or no fish shouldn't require a filter.
- Bradshaws, 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: allow 1,000 L/h per 10 cm of width.
- Aquascape, Pond Builder's Bible, chapter 7: pumps and electrical: 1,500 gph of flow for each foot of spillway width; pumps deliver less than their rating as total dynamic head rises.
- Ofgem, Changes to 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.
- US EIA, Electric Power Monthly, table 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.