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fish_4_all 09-20-2007 10:24 AM

DIY Sponge Filter
(The diagram doesn't show it best but 4-8 holes in each row will work best for best circulation. jst make sure not to degrade the integrity of the pipe so it stays sturdy. Four 1/4 inch holes or 8 1/8 inch holes or something inbetween should work best. Use your judgement but as long as the tube stays strong, I don't know that you can put too many holes in it.)

The tube can be either an uptake tube from an undergravel filter a piece of PVC pipe. The length of the pipe can be customized to whatever you want.

#1 Cut the pipe to length
#2 Fit the sponge(s) to the pipe. I recommend at least 3 sponges so you can rotate them out to clean them. Round will work better. Cut the sponge so it is about 3 inches in diameter. It can be narrower but don't go too wide or circulation will be hindered. It will also work better to cut actual circles out of the sponge just smaller than the pipe so it fits tight and there is not much compacting of the sponge to block water flow.
#3 Fit the sponge(s) again and mark the top of where the ponges fit moving them up about 1/2 inch from the bottom.
#4 Use either hot glue or silicone to fill the bottom of the tube to about 1/2 inch. Place some wax paper under the end so you don't make a mess and it can sometimes be removed fairly cleanly.
#5 Drill 4 or more 1/4 inch or smaller holes around ones section of the tube starting just above where you filled to just below where the sponges come to on the tube. Make at least one row for each portion of sponge used but the more holes the better. (See diagram)
#6 Cut a length of air tubing as long as you need it to get to the air pump and down into the bottom of the tube. Connect an airstone and turn on.

Adjustments may need to be made to the sponge thickness and tube height but only time will tell as to how clogged the sponges might get. If you find that there is not much mulm collected on the sponge you might need more or larger holes or need to turn up the airflow or need to cut the sponges down a little to improve circulation.

Please add to this, the more options a person has the better.

littlebabyfilly 09-20-2007 09:38 PM

so do you put the air stone under the sponges? im a little confused

fish_4_all 09-21-2007 12:03 PM

The airstone goes at the bottom of the tube. The airstone is green and the tubing is the dark color.

jim21 09-21-2007 08:38 PM

Great minds think alike....

About the time you were posting that, I was constructing the fliter mentioned below. :)

I needed a really small sponge filter for a fry tank, and these are some REALLY small fry, everything I was seeing at my LFS had sponges with holes large enough for the fry to fit in. So I devised my own solution, with a back up plan consisting of going to a not so LFS in case it didn't work.

I took about 6" of undergravel tubing, some HOB filter media, stuffed it in the bottom of the tube (about 2/3 inside tube 1/3 outside), and put the air stone on top held down with a extra heater suction cup holder. After a few days the filter media is turning brown so looks like its working!

My goal was some filtration with as little disruption to the fry as possible. They can swim by it and not get caught in it, yet its still removing some waste. I do very small daily cleanings so I think that balances, and they are almost big enough for me to put a regualar size filter (like yours) in.

Thanks for the great info!!

Elahrairah 10-13-2007 08:41 PM

I made one of these for my hospital tank. Haven't needed to use it yet, but I keep it running in one of my 10 gallon tanks to keep the bacteria up. Fish gets sick, he goes in the 3 gallon with some water from the 10 gallon and this filter....I assume it will be enough, but like I said, I haven't tried it (knock on wood).

verbosity 12-04-2007 12:35 PM

Has anyone taken pictures of their finished product of this filter?

iamntbatman 05-07-2008 10:20 PM

Wow this is an old thread, but I was thinking about building one of these. If you used a powerhead instead of an airstone, do you think this could serve as a means of mechanical filtration as well?

hpt84 05-09-2008 01:28 PM


Originally Posted by iamntbatman
Wow this is an old thread, but I was thinking about building one of these. If you used a powerhead instead of an airstone, do you think this could serve as a means of mechanical filtration as well?

Airstone or powerhead will provide mechanical and biological filtration. People usually use airstone because it is cheaper and provide ton of oxygen.

fish_4_all 05-09-2008 04:03 PM

An airstone and/or a powerhead will provide both biological and machanical if coupled with the right media.

A sponge filter can be run off of both for sure but make sure you get the right ones for the other. Loose sponges and filter material that have a fast flow only need an airstone to work. There are sponge pre filters and other sponge filters that are so dense it almost require a powerhead to run enough water thought them to make a difference.

Also, remember that if you are changing out the media on a regualr basis all it does is provide mechanical filtraiton because it doesn't stay in the tank long enough to build up beneficial bacteria.

iamntbatman 05-09-2008 04:09 PM

For my next tank, I'm thinking about doing a combination UGF/sponge filter in addition to an HOB. Do you think if you used powerheads that you could simply poke holes in your UGF tubes and put sponge material on the tubes before you stick them into your filter plate to get a dual purpose filter? Or would all of the water go through the path of least resistance leaving either the sponge or UGF worthless?

I was just thinking of interesting ways to layer filtration.

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