Eco-Saturday: DIY pond filter

The motor in my pond’s all-in-one pump and filter burned up a few weeks ago, as motors are wont to do. Rather than spend $120 to replace the whole unit, I decided to install separate components this time around so I’ll be able to replace individual parts as they wear out.

After some online research, I decided I could make a biofilter a lot cheaper than I could buy one. Here’s what I came up with for our pond, which has a capacity somewhere around 50 gallons. A bigger pond obviously will require a bigger bucket and more pot scratchers and Scotch-Brite pads.

1-gallon tub with a lid (I used an empty ice-cream bucket)
10″ long PVC pipe, threaded at both ends (in plumber parlance, these are called “nipples”; you’ll want to take your pump along to the hardware store to make sure the nipple you buy is the correct diameter to fit)
Teflon tape
12 plastic pot scratchers
6 Scotch-Brite pads
Pond or fountain pump

Hole-saw bit the same diameter as your PVC pipe
Good-sized drill bit (at least 1/4 inch)
Utility knife and/or sharp, heavy scissors


Start by preparing the bucket lid. Cut a hole in the center of the lid to accommodate the pipe, drill holes all over the lid, and cut a notch at the edge of the lid to accommodate the cord on the pump. (Note: The holes you see above are much too small. I used a 1/8-inch drill bit, thinking it would be sufficient, but the holes clogged quickly, dragging down the flow and putting unnecessary strain on the motor. The pump and filter functioned much better when I enlarged the holes to about 1/4 inch.)


Wrap one end of the nipple with Teflon tape and screw it into the pump.


Slide the free end of the nipple through the hole in the lid.


Set the pump in the center of the bucket and tuck the pot scratchers and Scotch-Brite pads around it. These materials will serve as a medium for growing the good bacteria your pond needs to break down organic material and keep the water clear.


Snap the lid onto the bucket, running the cord out through the notch you cut.


Set the pump in the bottom of your pond, holding it down if necessary for a minute or two to let it fill with water so it doesn’t float back up to the top. Plug in the pump and watch the clear water come out the top. (Note: You may need to adjust the flow rate on the pump to control the height of the spray.)

If you have a yard, and you don’t have a pond yet, I highly recommend building one next spring. Our bees love ours, as do the local toads, who bred out there all summer.


8 thoughts on “Eco-Saturday: DIY pond filter”

  1. Brilliant. I have submerged my pump in a big heavy duty plastic plant pot to keep the Racoons away from the pump, they take it apart! Then I have tomweightnthe whole thing down with big stones. This is a pain to take apart to clean the pump. I will now put the ice cream filter pail inside the flower pot….won’t have to dive in to clean it so often.
    Again, brilliant and thanks!

  2. Excellent! I would like to know what kind of pump did you get to make this pond filter, I have an understanding there are different gallons per hours capacity and I am really interested in doing one myself.
    Thank you for your DIY explanation!

    1. I don’t remember. I think it was one of the larger fountain pumps, which was way bigger than my little pond needs. The strong suction of this pump has actually caved in the plastic bucket. The filter still works perfectly, but reassembling it after cleaning gets tricky. For a pond under 50 gallons, I’d go with the cheapest, smallest fountain pump you can find.

  3. Smart Lady! Just finish building a backyard waterfalls, we are definitely going to try this. Thanks for sharing

    1. Frequency depends on the size of your pond, where it’s situated (shade vs. direct sunlight), how many fish you have, what kind of plants, etc. This one was in a shady corner of the yard I could see from the deck, so I just glanced over there when I put the dogs out, and if the pump had slowed to a trickle, I unplugged it and cleaned it out. (I’m using past tense because we moved in late 2017, and I don’t know whether the buyer kept the pond. Probably not.) You just open the lid, dump everything out, hose it off, and put it back together. Takes about five minutes. Algae was rarely a problem with this pond, but I used water lettuce to shade the water, and its long roots would grow down into the filter and clog the pump intake every few days. In a deeper pond, this wouldn’t be an issue. Duckweed, which has much shorter roots, is less prone to clog the filter in a shallow pond.

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