Start with volume
A common goal is to turn over the whole pond once an hour. Koi ponds often aim for more. A pond of two thousand gallons needs about two thousand gallons per hour.
Add the waterfall
A waterfall needs roughly one hundred to one hundred and fifty gallons per hour for every inch of weir width, depending on the sheet you want. A twelve-inch weir needs about twelve hundred to eighteen hundred gallons per hour.
Account for lift
Pump ratings are quoted at zero lift. Each foot of height reduces flow. A pump rated for three thousand gallons per hour at zero lift may deliver less than half at six feet of lift.
Pipe size and friction
Small pipe and many bends cut flow. Using larger pipe and gentle sweeps lets a smaller pump do the job.
Efficiency matters
Pumps run all day. An efficient pump saves electricity over its life. Variable-speed pumps let you adjust flow for day, night and season.
Use the tool
Our pump tool combines volume, waterfall width and lift to suggest a range. It is a starting point, and we fine-tune on site.
Size for the waterfall first, check the lift and choose an efficient pump with a little extra capacity.
