What size pump do I need?

This section will explain the factors to determine the right pump for your application. This is very important if you’re buying a new pump or find that you’re continuously replacing the one you already have. Keep in mind the absolutely easiest way to make sure a pump is right for your application is to take the guess work out of the equation and use an Aquascape pond or pondless kit which includes the properly sized pump already. It is important to understand that all pumps have an operating point where the best energy efficiency and the best life expectancy will be achieved, also known as the BEP (Best Efficiency Point). You can also go through a detailed video training segment on pump sizing at aquascapeacademy.com under the project specification course.

  1. Determine the flow requirements you wish to achieve. As a general rule of thumb you can use 1,500 gallons per hour per foot of spillway width for residential waterfalls. The flow rate can vary depending on the size and shape of the rocks used in the waterfall. Flat rocks may require less flow as the water sheets over the surface and round boulders will require more flow as the water flows between the joints of the stacked stones.
  2. Determine the total head, in feet, for the project. This is a combination of vertical lift from the surface of the pond plus the friction losses in the pipe (general rule of thumb: add 1 foot of friction head loss for every 10 feet of pipe length. For example: a 50 foot long run of pipe will have an estimated 5 feet of friction loss).
  3. It is also important to select the proper pipe diameter for the flow rate of your pump. Using too small of a pipe will add additional friction-loss. Think of it as trying to drink a milkshake through a cocktail straw.

Here’s an example using what we’ve learned. My pump will push 20 feet horizontally, and will push 5 feet upward vertically using a 2 inch pipe. My total head pressure is approximately 7 feet. I know I need 3,000 gallons per hour to have proper filtration because I have a 2 foot wide waterfall, so I need a pump that is rated for 3,000 gallons per hour at 7 feet of head pressure.

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