Homemade Undergravel Filter (from bucket lid)
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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.

Reading about the under gravel filters, I decided that was the way I wanted to go. A siphon is used to clean the rocks on the bottom, all you do is siphon water from the bottom and the muck is pulled up with it, you don't have to remove the rocks or anything. I have a couple of 5 gallon bottles that were previously used in a water cooler -- they are great for changing the water.

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.

ONE SLIGHT PROBLEM !!! The air pump was a bit noisy, so my wife wanted it on a timer to turn off at night. After 3 days of this, a horrible smell came over the room, smelled like one of our cats was spraying. Turns out it was ammonia from the fish tank. I have read that the bio filter needs to have water constantly running thru it. Since my bio filter was the rocks at the bottom of the aquarium, and they were constantly submerged, it would be OK to shut off the air pump (and water flow) at night, and the bacteria would still be alive. This was not the case, and shutting it off for 6 hours every night was not acceptable. So I fixed the problem by suspending the air pump from a string, now it is very quiet and the air pump runs 24/7. It is even more quiet than the original power pump we had.

BENEFITS - I sure do like this filter system better than the commercially bought pumps that hang over the side of the tank. It is SO EASY to clean with the siphon, and there is less clutter in the tank. Some people have told me that you never remove the filter from the bottom, and others have said they fully dissasemble and clean the rocks / filter about once a year.