It's very easy to make your own sponge filter. The small filter sponges
that comes with most filters are not large enough for big tanks so it's
advisable to make your own.
This is not a very good looking filter but it's very powerful and you
wont need to clean it more than ones every six months if that.
To make it you need a sharp kitchen knife, a peice of hose, a hammer,
a nail, a plastic tube like the ones used for electrical installations,
a peice of filter sponge and a powerhead.
The powerhead should be of suitble power for your tank. This means
that it should pump at least twice as much water per hour as your tank
Filtersponge can be bought at most pet-shops. I have found it better
to use sponge with larger pors since it seems to house the beneficial
bacteria better without clogging up.
In this example I have bought a big cube of filtersponge to make two
large triagular filters for two 55 gallon tanks in my fish room. Since
this will be breeding tanks in a fishroom I make large filters and it
does not matter that the sponge is blue. I have seen black, green and
blue filtersponge on the market but after a while they all look about
the same so it is not all that important unless you need it to look
natural from the very start.
I cut the cube diagonally into two triangle shaped peices.
Mark out how much of the plastic tube that will be inside the sponge.
Then make wholes with a hammer and a nail all over the part of the
tube that will be covered by the sponge. Drive the nail all the way
through so that you make two wholes at a time.
The wholes can of course also be made with an electric drill.
You need to tap the bottom end of the tube with something. I have used
a peice of styrofoam in this example.
First make a small hole in the sponge with your finger and then you
can push the actual tube all the way to the bottom of the triangular
peice of sponge.
Then you place the powerhead on top of the tube and conect a hose to
the outlet so that you can point the out going water flow at the surface
in order to get more oxigen into your tank water.
Here is one of my filters when it is mounted in a tank.
Easy to make, cheap and powerful....but pretty ugly. Good luck with