How to Size a Pond Filter

Backyard garden ponds offer a relaxing atmosphere and can be home to many types of fish. Like any other manmade aquarium or pond, they need proper filtering and oxygenating to remain hospitable to fish. Without a filtering system, the pond will become murky and create an unfavorable environment for fish and other plant life. To size a pond filter, know the volume of the pond. This is a fairly easy calculation that requires taking simple measurements.

Instructions

1. Calculate the volume of your pond. Depending on the shape of your pond, you will either need a length and width measurement, or just a diameter measurement. For all types, you will need a depth measurement (see Reference 1).

2. Calculate the size of filter needed for your pond based on the pond's volume. A filter's surface area must to be approximately 10 to 15 percent the size of your pond. For instance, if your pond has a volume of 16 cubic feet, you'll want the surface area of the filter to be 1.6 to 2.4 square feet.

3. Look at the pond pump systems and figure out which filter to purchase. Depending on the pump system you will be using, the filters may come in different sizes. The surface area of the filters should be listed on the packaging.

Tips & Warnings

• Also calculate the filter size by using the surface area of your pond. The filter should be at least 1/3 of the surface area of your pond (see Reference 2).

• If you have a large stock of fish or a Koi pond, increase the filter size to 15 to 20 percent of the pond's volume or 1/2 of the pond's surface area.

References

• Van Ness Water Gardens: Pond Volume Calculator
• ABCPonds: Pond Filter Buying Guide