Koi Rescue
Phoenix Arizona

Home Made Undergravel Filter (from bucket lid) - 25 Gallon Octagonal Aquarium

I was using a standard type filter that looks like a black cylinder, which hangs from the top edge of the tank. It has a pump in the bottom, and pumps water up thru the cylinder, then dumps it back into the tank. This filter originally came with a filter pad in it, but I removed it and filled it up with rocks to create a bio filter. It worked OK, but didn't seem that effecient, and was a pain to clean because I had to remove the filter and shake loose all of the muck in the sink, and sometimes the rocks would flip out and I would have to dig them out of the disposal. So then I started using a big mixing bowl to clean the rocks, and it was just a pain.

I could have purchased a filter, but figured it was just a grate with holes in it, and I had a bucket lid laying around that fit perfectly in the bottom of the tank, so I decided to try using it first. First thing I did was drill a bunch of holes in it to make the grate.

Next problem was how do I attach the vertial bubbling tube? I thought of a number of ways, and then went with this simple method - I simply cut a PVC elbow, then sanded inside the elbow so the PVC would poke thru the other side.

A single stainless steel screw, and presto, it was attached to the bucket lid.

Well that was quick, it only took about 20 minutes to make this, adn of that most of the time was drilling all those little holes.

Here it is in action, the way it works is that an air stone is put in the PVC pipe near the bottom. The bubbles rise up the tube and pull water with it. That water is pulled from the tank thru the gravel at the bottom, and thru the bucket lid grate. This provides the circulation over the rocks, so the bacteria grows on it and eats all the fish poop.