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Pump Sizing help

Just like your body has a heart to circulate healthy blood through your system, your pond has a pump to circulate the water over the falls, providing beneficial aeration for your pond critters and plants. Choosing the right pump is essential for ensuring that you create an adequate flow of water for your waterfall or stream, which in turn maintains water quality that fits for your pond ecosystem. When doing your shopping, here are some things to consider:


Water needs to circulate through the filter at least once every 2 hours. This means that if you have a 1,000 gallon pond, you need a pump that can produce at least 500 gallons per hour or GPH. If you have fish, then it is best to double the pump's capacity to ensure that your water stays clean. A common misconception is that pump size is only related to pond size; however, the size of a waterfall, stream, or fountain and filter is typically the deciding factor for which pump will be best in your application When sizing a pump for a pond there are a few other considerations.

  • How high will the pump have to lift water?
  • Do you have a waterfall, fountain or statuary?
  • Will there be filters?
  • Friction Head loss due to friction from water travelling under pressure in hose sizes, type of materials, fittings

All of these variables reduce the amount of flow, which could affect water quality and clarity.

  • Head pressure : A combination of the vertical distance from the water surface to the top of the waterfall and length of tubing. A foot of vertical height or 12' of tubing is equivalent to 1' of head pressure. Therefore, a feature that is 3' tall with 16' of tubing would have 5' of head pressure.
  • Flow Rate : The average amount of water moving over a waterfall is 1,500 GPH for every 1' of width. Therefore, a waterfall that is 2' wide would need a 3,000 GPH pump. If you are looking for a heavier flow, calculate your flow using 2,000 GPH per foot.
  • Putting it Together : You may have noticed that our pumps have the flow rates listed different head pressures, so you just have to match up the numbers. In our example, if you wanted your feature to have a heavy flow then you would need a pump that can produce about 4,500 GPH at 5' of head pressure would be the perfect fit because at 5' of head pressure, this pump produces 4,500 GPH.

When you are sizing a pump to your pond & water feature its not a bad idea to go with a pump with slightly more flow than needed. Because you can just put in a ball valve on the discharge side of the pump to slightly reduce flow by closing the valve with out harming your pump and having the ability to ajust flow

Tip For best results, choose a higher flow rate for koi ponds, turning your pond 1-2 times an hour.