After spending many years trying different sponge filters for my fish room, and never being content, I finally decided to create my own. The filter I am making here is a 4"x4"x4" sponge filter, however you can make them into whatever size you want. This is what I love about the DIY sponge filters. So here we go.

First you need the sponge block. If you only need a few you can go to pleco caves, http://plecocaves.com/Poret.htm , and purchase a 13"x13"x4", 30ppi piece to make nine filters. If you want to make a lot I would advize going to swiss tropicals, http://www.swisstropicals.com/Poret%2 ... r%20Foam%20Pricelist.html . Here is the piece I purchased from pleco caves.



Once you have the sponge material you will need to get your supplies together.
- 1" thinwall tube, or you can use pvc pipe
- 4"x4" slate tile(for the base)
- aquarium silicone
- airline tubing
- airstone
- fine toothed saw or knife
- drill, drill bit and hole saw


Start by cutting the block of foam into whatever size you need. I chose to cut mine into 4x4 pieces with a bandsaw. You can use a fine tooth saw or knife but make sure to cut swiftly in one direction. If you saw back and forth you will pull the foam and tear it.


Once you have your foam cut to desired size the next step is to drill the hole for the uplift tube. There are two ways you can do this. The first is to submerge the foam piece in water, making sure to get all the air out of it, and put in the freezer. Once it is frozen you can drill your hole. Make sure you do this before it melts or you will end up tearing the foam and having to start all over. The other method, which is what I do, is to use a hole saw and just drill your hole. Although this does not make a perfect hole, and does pull on the foam a bit, it works fine for me. You do not need a perfect hole just one that your uplift tube will fit in snugly. If you are drilling the hole with a holesaw be sure to choose a much smaller one than the size of the hole you need. The reason for this is that you will pull and tear the foam a little which will actually make the hole larger than the size of the holesaw. Be sure that you do not drill all the way through your piece of foam, you only need to go down about three inches.


Once you have the hole drilled now you have to prepare the uplift tube. You can use either a piece of 1" thinwall rigid tube that you can buy from most petstores or a piece of pvc. I like to start off by pushing the uplift tube into the hole of the sponge and deciding where I need to cut it off. Then I mark a spot right above the foam to drill a hole to put the airline tubing through. Once you have drilled the hole for the airline tubing drill as many holes below it as you want for the water to be pulled through the sponge. After you have drilled your holes insert the airline tubing into the hole at the top and attach your airstone to it. You do not have to use an airstone but the more bubbles you have going through the uplift tube the more water that will be pulled through the sponge.


Now all you have left to do is silicone your slate tile to the bottom of the piece of sponge and insert your uplift tube. I prefer to use natural slate tile as many tiles have glazing on them and this glazing will break down over time and could harm your fish. When siliconing your base to your piece of foam be sure to use aquarium silicone as many silicones out there have mold inhibitors in them that will kill your fish. Let the silicone dry for 24-36 hours and your new DIY filter will be ready to put in the tank.

So does the height of the uplift tube matter?

Yes it does because it directs the bubbles farther up rather than them leaving the tube and going anywhere. At least this is my theory!

Intuitively I'd think you'd get more water moving with a longer tube.

Yes I would think the longer the tube the more water flowing upward because it is not fighting downward currents produced by gravity, but then again if the tube were too close to the surface it might actually reduce the amount of water flowing through. This is just a theory but if you were to place the top of the uplift out of the water then there would be less water flowing through as opposed to placing it below the surface. As the air bubbles rise, along with the water that is being forced up around them, the bubbles continue to rise until they hit the surface. Not all of the water goes straight up; instead it is forced horizontally due to currents and gravity. The upward current produced by the bubbles is not strong enough to break the water surface much so the closer the tube is too the surface the more the downward currents would affect the upward moving water.

Great details.

You should submit this, if you haven't already, to the ALA. It would make a great article; it's very useful.

Perhaps the ALA can coagulate all of those 'funky' DIY's into a single publication for the next generation.

Thanks shadow. If there is a way they can use this post to do an article I am fine with it. I am working on writing it up as an article now to include on my website, maybe when I am done I can just send it to them.

Actually now that I think about it it would be nice to have a section on the forum to submit articles. Or atleast create a sticky thread on how to submit them.

Great article man! I was thinking of a way to make them, but this is perfect! Hopefully I'll put a couple together for some 55 gallon barrels I'm picking up soon!

That would be great; the wealth would be appreciated, I'm sure by all who read it. I'm waiting to get home to try some of that DIY stuff myself.