Build Your Own Pond Filter

If you decide to build your own pond filter, there are several designs that you can use, depending on the size of the pond and the amount of filtration needed.

You can go with a homemade pond filter with a size as small as a 5 gallon plastic bucket, or as large as a 75-gallon stock tank. The concepts are generally the same for both sizes. The bigger your pond, the bigger the filter you will need to consider building when you decide to build your own pond filter.

The directions I provide for you here to build your own pond filter are based on my own experience with a home made pond filter made using a stock tank. I found these directions on Skippy’s website.

Building a pond filter is not hard and going with a do it yourself (diy) pond filter can save you hundreds of dollars. But, if you are not comfortable building a pond filter yourself, then by all means purchase one of the many good commercial filters at a pond supply outlet.

Build your own pond filter

Pond Filter Parts List
  • 1 – Rubber stock tank
  • 1 - length of 1 1/2 inch PVC pipe.
  • 1 - PVC tee.
  • 3 - PVC elbows.
  • 1 - 1 1/2 inch to 1 1/4 inch threaded nipple reducer.
  • 1 - 4 inch closet flange
  • 1 - plastic egg crate style overhead 2x4 light grate found in the ceiling tile section of any Home Depot or similar home improvement store. It is nothing more than a ceiling light grate panel.
  • 4 - 1/4 inch by 1 1/2 inch bolt, nut and washer combinations
  • Filter medium. – use lava rocks, or floor scrubber sponges, or anything that your beneficial bacteria can grow on.


Steps to build your own pond filter

First of all you will need a rubber stock tank. The one I used was a Rubbermaid brand purchased at Tractor Supply Company, but there are several other brands out there. Decide where you want to place the tank outside of your pond. You will want to point the drain plug away from where it will drain in to the pond and you will want to make sure it accessible to you to open and close it during cleaning. You will want to be able to attach a rubber hose to this drain and drain the filter into your flower or vegetable garden. You won’t clean this often, but it is helpful if the plug is accessible just in case.

On the top flat face of the tank, draw a circle using the closet flange as a guide. Cut out this hole. Using the closet flange as a guide, cut out the mounting holes. Mount the closet flange on the outside of the tank, and use a cut piece of the egg create on the inside to block filter media from flowing out of the hole. Be sure to silicone the flat area on the flange before installing it.

Building a Pond Filter

If you are placing the filter behind a waterfall, you will want to be sure to put some pond liner behind the overflow flange to keep the water from running behind the filter.

Cut the PVC pipe so it will fit in the bottom of the tub with the tee and elbows attached. You want the bottom elbows to face in different directions so that you will get the swirl effect.

Building a Pond Filter

Cut another length of PVC to extend up from the tee. On top of this PVC pipe, put another elbow. Inside this elbow, put the threaded nipple reducer. Do not cement any of these pipes into place.

Now, cut the egg crate to fit where it will rest on the bottom ridge on the inside of the tank. The purpose of the grate is to create a space between the bottom of the tank and the filter media. This forms a sludge area for bacteria to grow in. Cut a hole in the center of the grate for the PVC to fit through.

On top of the grate, put the filter media. You can put another grate on top of the media, but this is not necessary.

Top of Biological Pond Filter

Put the top elbow on, and align to the direction from which it will come from your pond. Put the threaded reducer on and connect up your pump. If you have a submersible pump, have it as far away from the filter as possible. Also, do not put your pump on the very bottom of the pond, just in case it accidentally pumps the pond dry. If you have it up off the bottom, it will leave a little water in there for the fish.

Building a Pond Filter

You can put water plants in the top of the filter, which will eventually cover it so that you cannot see it. You can have the overflow coming out as a waterfall.

Building a Pond Filter

After you build your own pond filter, it will take 6 to 8 weeks for the biological action to get established. Be patient.

Do not clean this filter often. It will kill the good bacteria you have worked so hard to establish.

Biological Filter covered with plants

Deciding you want to build your own pond filter can be rewarding (because you can say you did it yourself) and it can give your pond the needed biological filtration at an economical price.

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