# help with diy sponge filter(air pump)



## BoiBJ

does anyone know how to make one ? i want to make one as simple and low cost as possible! Also can someone explain the principles on how a sponge filter works? I seen tutorials and procedures that sometimes use a tube with holes and placed in the sponge along side a airline and airstone, and some with only a sponge and air pump?


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## BillD

The idea of a sponge filter, like any filter, is to have water flow through it. Generally sponge filters will consist of an airlift tube with a sponge around it in some form for the water to be drawn through. They work because of gravity, and the air pumps don't actually "lift" the water. By filling a column ( usually a tube) with a mixture of water and air bubbles, you create an are that is less dense than the water in the tank. As a result, the water in the tank tries to fill this area of lower density and you have flow. You can demonstrate this principle for yourself by taking a piece of rigid tubing or pipe, holding your hand over the end to close it and submerging vertically it in a container of water. If you remove your hand, so both ends of the tube are open, the water will fill the tube from the bottom. This is how the airlift works.
To make a sponge filter you would place a tube with openings in a sponge and add an air line. The openings, lets say holes drilled in a capped tube or pipe, need to be covered with the sponge so water has to pass through the sponge to enter the tube. That is it in it's most basic form. However, sponges generally float, and need to be weighed down, The longer the lift tube the more flow. So, there are many ways to actually make one that will work, and some ways are easier or better than others. I have some home made sponge filters, but most of mine are now ATI Hydrosponges.


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## BoiBJ

BillD said:


> The idea of a sponge filter, like any filter, is to have water flow through it. Generally sponge filters will consist of an airlift tube with a sponge around it in some form for the water to be drawn through. They work because of gravity, and the air pumps don't actually "lift" the water. By filling a column ( usually a tube) with a mixture of water and air bubbles, you create an are that is less dense than the water in the tank. As a result, the water in the tank tries to fill this area of lower density and you have flow. You can demonstrate this principle for yourself by taking a piece of rigid tubing or pipe, holding your hand over the end to close it and submerging vertically it in a container of water. If you remove your hand, so both ends of the tube are open, the water will fill the tube from the bottom. This is how the airlift works.
> To make a sponge filter you would place a tube with openings in a sponge and add an air line. The openings, lets say holes drilled in a capped tube or pipe, need to be covered with the sponge so water has to pass through the sponge to enter the tube. That is it in it's most basic form. However, sponges generally float, and need to be weighed down, The longer the lift tube the more flow. So, there are many ways to actually make one that will work, and some ways are easier or better than others. I have some home made sponge filters, but most of mine are now ATI Hydrosponges.


Thanks Bill I was kinda puzzled on how it works, but you explained it very clearly and I understand how it works now because of you. Thank You!! Ok so the materials I'd need is rigid tubing/pipe, airline, sponge and air pump and maybe air stone? Also I have sand substrate so would that cause any problems?


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## splur

Look on ebay for "biochemical sponge filter". You can get either the large one which sits on the bottom of the tank or the one that goes over inlets for 2$ ea with free shipping. I don't think you could possibly make it for cheaper.


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## PrimO

I made one today because I couldn't find one that would fit my 5 gallon tank... Cost me more just for the sponge then the sponge filters were selling for.. But hey, I guess I can make more right?....
Pretty happy with mine so far though, the ones at the lfs had holes at the top, if you make them on the side the air will gather at the top and release short bursts through the holes causing more pressure and hopefully more water displacement through my sponge.


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## absun

Here is one i built. all you need is a airlifting tube/airstone from pet store and plastic box/sponge from dollar store.

Put some stones in the bottom of the plastic box so it won't block the flow.

http://www.gtaaquaria.com/forum/showthread.php?t=28793


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## getochkn

PrimO said:


> I made one today because I couldn't find one that would fit my 5 gallon tank... Cost me more just for the sponge then the sponge filters were selling for.. But hey, I guess I can make more right?....
> Pretty happy with mine so far though, the ones at the lfs had holes at the top, if you make them on the side the air will gather at the top and release short bursts through the holes causing more pressure and hopefully more water displacement through my sponge.


I have the small, short Seapora one from Big Al's that fits my 5gal fine with my tiger shrimp. Had to cut the plastic tube down a bit, but the sponge isn't tall like the larger ranges.


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## PrimO

I got lazy and didn't want to travel, I checked two places and the smallest one I could find was about 2 inch high, and like 7 or 8 inches wide! So it seemed.. Figured I would end up hacking it up any ways..


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## FlyingHellFish

Would a power head connected to a small sponge make any different if your tank doesn't have a lot of debris?

Would an internal filter work just as well? You know, the one with just a form insert.


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## absun

Power head + sponge should provide similar result as sponge filter in terms filtering, but sponge filter will be better off in terms aeration


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## joe

i dont understand.

are you making a filter with just air?
how do you push the water up and throu the filter?


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## HOWsMom

joe said:


> i dont understand.
> 
> are you making a filter with just air?
> how do you push the water up and throu the filter?


Read BillD's post - he explained it better than I've heard before.


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## joe

is there only a filter on one side or both? and how does the air work?

i fugure if you put a filter on the top and bottom and put air above the bottom filter it will push bubbling water up above the top filter..

airating the tank aswell as filtering the water twice? but rather slowly??
am i totally off or would that work?


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