# Help Me Understand Sponge Filters



## seltzerwater

Air pump powered ones.

Well, mostly I get what it does. Water displacement draws water into the sponge which filters out debris. But where does the water exit? From the sponge back into the tank? Above the sponge? Through the tunnel where air comes in and water displacement occurs? I want to add some activated carbon to the sponge filter similar to penn plax's small world filter, but I don't want the carbon to be exposed to debris like their filter. 

This is my idea

http://img153.imageshack.us/img153/4139/filteridea.jpg

I want to know how the exit water flows to know if it will be passed through the carbon in that setup.

Thanks for your advice!


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## Angel079

Dang we just had a discussion about that few days ago and I can not find this thread any more :-(

The water exits on the top with the bubbles; here's a good sponge picture Bio Foam Single Sponge Filters, Sponge Filters | Pet Solutions this is how it will sit in your tank and at the top you'll have the bubbles & water mix come out.

Why do you need carbon so desperately in your tank if I may ask???

You pretty much would wanna stuff the carbon in the tubing if I understand your drawing right? There'll be either 1 outta 2 things happening there A) You stuff it so teight with carbon that the actual filter can't work proper any more b) you keep the carbon loos enough so the filter can work but then it'll float out the top.
If you look at the picture form t he link above the bottom bent tube where the sponge sits on; if ANYTHING at all that's where i'd try to add the carbon


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## seltzerwater

oo thanks angel!

Hmm, I was hoping to put the carbon surrounding the tubing but I see now that the carbon wouldn't interact with the water that way if there are no grooves for water to flow through. I had a design that would work with powerheads but I wanted the air pump for my betta tank. 

TBH I'm not even sure if I need carbon for 1 little fish, but it's just something cool to think about 'cause I fancy myself to be a pioneering DIYer (*laughs*)

I think I'll try to put some panty hose/mesh around the rigid air tubing opening, that way air bubbles can still exit, and then keep the carbon loose (not packed full) that way it can float around and still do something for the water. Any merits? 

Thanks!


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## Angel079

You only need carbon if you're getting rid of meds.
On top if you have plants in there carbon is actually indeed bad.

But if you wanna DIY a super awesome "sponge" system; look up Hamburger Mattenfilter on googel; I used to built them back int he days for my tanks and they work awesome spc for larger tanks like a 55g


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## seltzerwater

hmm i heard carbon gives crystal clear water, if i'm not planning on using micronutrient fertilizers for the plants will the carbon be okay? although water changes will help, will it still be ... hmm crystal clear? iono if that's the right word to use here or maybe i'm just expecting too much out of carbon lol


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## Angel079

I have clear water in all tanks and no carbon. If you have water issues then either you're overfeeding; not doing proper water exchanges or issues with your filter in general.

You have nutrition coming from your source water, your fish, their waste etc; whether you use add liquid ferts or not this will be filtered out to some extent and chances are great your plants will not thrive the way they could with carbon in that tank.


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## redchigh

Angel079 said:


> I have clear water in all tanks and no carbon. If you have water issues then either you're overfeeding; not doing proper water exchanges or issues with your filter in general.
> 
> You have nutrition coming from your source water, your fish, their waste etc; whether you use add liquid ferts or not this will be filtered out to some extent and chances are great your plants will not thrive the way they could with carbon in that tank.


The whole "carbon gives crytal-clear water" argument was created by the carbon manufacturers. In an established healthy tank, (especially one with plants) the carbon does way more harm than good. For example, my power filter came with a carbon "cartridge" in a mesh bag. After a few months, I took the carbon out, and filled it with filter floss.
Now, I don't think I'll ever have to replace anything in the filter- just take the floss out, rinse it out, and put it back in.  On the rare occasion that the biofilter mesh is filthy, I leave the mesh/floss cartridge in and rinse the biosponge instead. That way the floss holds bacteria to recolonize the bacterial sponge thingy.


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## seltzerwater

ah, darn, corporates

i ended up making a carbon thingie before i read the last few posts, here's my complleted filter

http://img718.imageshack.us/img718/2739/pic0188.jpg

The water will travel through the grooves in the plastic and the large debris will get filtered out by gravel, and then the smaller ones by the inner layer of filter moss. Then it'll pass through to the inner tube and get carried out with the bubbles and pass through the carbon, which is secured with some sponge and a piece of rock. but i'll probably be taking out the carbon soon, but i still think it's pretty cool :3333


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## nomel

I used something like that in a beta tank and it worked great, but with gravel instead of carbon. The bubbles passing over the carbon (or in my case, rocks) makes a perfect oxygen rich home for the good bacteria...meaning your carbon will probably get a slime coat pretty quickly. This is _somewhat_ the concept of a fluidized bed filter.


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## LMychajluk

Pardon my ignorance, but are sponge filters basically the same (at least in principle) to the old-style in-tank bubble filter?









I bought one of these over the weekend for a 5g hostpital tank. It was ~$3.50, and filled it with foam and ammonia absorbing media.


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## Santaaa

Sponge filters are perfect without carbon. They never remove what you want it to anyways which is ammonia. You should never have to buy anything. I recommend getting ammonia remover as it removes what you want it too but you don't need it. Sponge filters are great. I just bought the filter pictured above. The Bubbler by Penn Plax. If you really want to have carbon you can buy one of those and put it in the tray and add filter floss. Instead of carbon use ammonia remover. Also if you use this filter make sure you get an aquarium rock and put in the filter to weight it down. It will float otherwise.It works great and I highly recommend using it.


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## iamntbatman

Well, sponge filters are designed to house beneficial bacteria that process ammonia into nitrite and eventually into nitrate. Ammonia removing filter media are, in my opinion, useless except possibly in emergency situations (and even then I can think of better options).


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## ron521

Flow rates tend to be slower when driven by airpumps, but a sponge can work fine as the only filter in the tank, depending on fish load and how heavily planted the tank is.

If driven by a powerhead, flow rates are higher, but the sponge tends to fill up faster, and requires cleaning more often. I've had powerheads collapse a sponge, due to the much higher suction as the sponge pores gradually clog.

Also, plecos like to eat sponges, so if used in a tank with a pleco, they will require regular replacement.


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