from the blog

How to Build Your Own Pond Filter

Care and maintenance


September 28, 2020

Your pond filter is perhaps the most essential piece of equipment when it comes to keeping your pond clean and healthy. Pond filtration systems circulate the water to prevent algae formation, to remove waste build-up and they may also facilitate the growth of beneficial bacteria. Because filtration is key to the success of your outdoor pond, you should not buy a cheap one or purchase one too small for your pond. If saving money is a necessity, however, you can build your own pond filter from scratch.

Materials Needed:Large plastic planter or stock tank3-inch plastic shower drainJig sawJoint compound1 ½ inch PVC pipe1 ½ to 1-1/4 inch threaded nipple reducer

DIY Pond Filter

The first thing you need in order to build your own pond filter is a large plastic planter or stock tank. Visit your local home improvement store to peruse your options. Next, trace around the plastic shower drain on the outside of the tank just below the rim. Cut out the hole with a jig saw, apply a bead of joint compound around the outside of the hole then insert the shower drain and press it firmly against the side of the tank to create a seal.

Measure across the bottom of the tank and divide the measurement by two. Cut two pieces of 1 ½-inch PVC pipe to 2 inches shorter than the measurement you just took and attach a PVC elbow to one end of each pipe. Connect the two pipes in the middle with a tee connector and insert a piece of PVC equal to the height of the tank vertically into the remaining connection on the tee. Top the vertical pipe with a 1-1/2 to 1-1/4-inch threaded nipple reducer then place the assemblage of pipes in the center of the planter or stock tank so the horizontal pipes rest on the bottom.

Position the elbows on the horizontal pipes so they point in opposite directions - this will create a swirling effect at the bottom of the tank which will increase the efficiency of the filtration. Cut a piece of rigid plastic mesh to the size of the stock tank or, if you are using a plastic planter, purchase a plastic sieve large enough to fit inside. Cut a hole in the middle large enough to pass the vertical PVC pipe through. The mesh should sit several inches above the bottom of the tank – elevate it with wooden blocks if necessary.

Fill the tank with your preferred filter media. You can purchase filter sponges from your local pet supply store, but regular dishwashing sponges and scrubber pads cost less and work just as well. These materials are ideal for use in pond filters because the pores catch unwanted waste and debris while also providing a place for beneficial bacteria to grow. Finish up your homemade pond filter by positioning it on the opposite end of the pond as your sump pump. Insert the hose from your sump pump into the 1-1/4-inch threaded nipple in the vertical piece of PVC and turn on the pump. The water will pass through the PVC pipes, swirl around the bottom of the tank up through the filter media and exit via the shower drain in the side of the tank back into the pond.

To turn your homemade filter into a more efficient biological filter, consider adding an EcoBio-Block Wave in addition to the sponges. EcoBio-Block products are infused with beneficial bacteria which naturally clear cloudy pond water, keeping it safe and healthy for fish. The EcoBio-Block Wave lasts for three years and can accommodate between 300 and 1000 gallons of water which means that it will keep working long after it becomes necessary to replace your other filter media. You can also install EcoBio-Block Waves along the bottom of your pond, instead of inside the filter, to clarify water and remove odors.