# DIY Sponge Filter



## Nameless

Just built one not long ago for my Betta's bowl. But really, I don't get how it works. How does blowing air into a sponge pull particles out of the water? It doesn't make any sense!

And mine keeps forming these stupid big bubbles that causes way too much turbulance on the surface of the water for the poor betta. How can I make the bubbles smaller?

EDIT: OKAY! So I took the rubber band off and it looks like that image of the other filter, only without the clear tubing. Anyway, so if that is how it is supposed to work then all is good with the world! Except that it still makes bubbles a bit too fast for the betta to hang out on the surface of the water with. Much smaller and more regular than before, but still too fast. I guess that is when this "air input" thing comes into play?

So... How do I change the air input on something that doesn't have any knobs or anything that I can actually mess with? I am going to Petsmart on Monday (or maybe tomorrow) for another plant, a second sponge and some kind of prop. So I'd like to know if it is something I need to purchase before then so I can add onto or change my shopping list.


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## bmlbytes

The air should not be going through the sponge at all. The sponge should be at the bottom, with air going up a tube sticking out the top of it. The rising air causes the water to move with the air, effectively pulling the water up and out the tube in the top.










You could use a limewood air stone to make smaller bubbles, but there is a chance your aquarium will fill with microbubbles if you do that.


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## smark

Nameless said:


> Just built one not long ago for my Betta's bowl. But really, I don't get how it works. How does blowing air into a sponge pull particles out of the water? It doesn't make any sense!
> 
> And mine keeps forming these stupid big bubbles that causes way too much turbulance on the surface of the water for the poor betta. How can I make the bubbles smaller?


What does it look like? Pics?


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## Betta man

I think he's using a homemade one. It should help if you put the sponge filter higher up and not as far down in the water.


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## AquariumTech

bmlbytes said:


> The air should not be going through the sponge at all. The sponge should be at the bottom, with air going up a tube sticking out the top of it. The rising air causes the water to move with the air, effectively pulling the water up and out the tube in the top.
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> You could use a limewood air stone to make smaller bubbles, but there is a chance your aquarium will fill with microbubbles if you do that.


+1 

For the bubble problem, you have a few choices. 1. Turn down the air input 2. Use an airstone 3. Use different type of sponge material 4. Change the design.

Even though in most areas in my life I am a DIYr, I usually keep away from that when it comes to filters, for a good reason. The money you spent on making a "diy sponge" is probably how much it would cost for a professionally made one, they are very inexpensive, not to mention the waste of time, and bad looks.


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## Mikaila31

You can make a DIY sponge with garbage though. I'd rather build my own then buy them. But I don't care about looks since all my filters just get buried by plants. Airpump are also too noisy for me and don't create enough flow.


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## Nameless

Hmm, alright. I am using one that I made at home, and it is pretty simple enough. I think my problem may be solved by the first one, as I closed off the way out because I didn't think the bubbles were supposed to escape so easily. I'll try a new method today and see what happens.

Secondly, Yeah, it is DIY and is currently near the top. But I would feel better if it could be closer to the gravel and thus near where all the fish poop falls. 

@AquariumTech, I am using an air stone already. And I have no idea how to change the air input. Will shortly be changing the design, and... Oh! I'll think about a different sponge if I find out that is what is wrong. It is a prefilter sponge that people have suggested that I use, so I am hoping I got at least that part right.

And I didn't use 'garbage', went out and bought everything new. Seems silly now, I guess, but I've never made one before. And I am not sure I've ever heard of people buying a DIY item?

And the picture...
I'll get it in a minute


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## Nameless

The thing on the top keeping it closed is a rubber band. I couldn't think of anything else. All the videos I found on it talked about just using a random dish sponge and cutting a hole just big enough to jam the air tubing into. I didn't really want to just use a dish sponge, though, and figured I had to make sure the air could only escape THROUGH the sponge.

EDIT: OKAY! So I took the rubber band off and it looks like that image of the other filter, only without the clear tubing. Anyway, so if that is how it is supposed to work then all is good with the world! Except that it still makes bubbles a bit too fast for the betta to hang out on the surface of the water with. Much smaller and more regular than before, but still too fast. I guess that is when this "air input" thing comes into play?

So... How do I change the air input on something that doesn't have any knobs or anything that I can actually mess with? I am going to Petsmart on Monday (or maybe tomorrow) for another plant, a second sponge and some kind of prop. So I'd like to know if it is something I need to purchase before then so I can add onto or change my shopping list.


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## emc7

Adjusting airline with a pinch just doesn't last. You are going to have to break down and spend on a gang valve or one of the little green knob valves.


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## Nameless

A... gang valve? Alright, no biggy. I don't mind spending money for my pets ^_^
You make it sound expensive though, is it? Will this... Pinch (what on earth is that?) thing work until I can get the money to buy one if it is expensive? 

Also, how does a gang valve work? How is it assembled? Are there other supplies needed?

EDIT: Sorry for so many questions. I keep racing around the internet for the answers, but I can never seem to find them. And I don't have anyone who is experianced with fish that I can go and talk to.


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## AquariumTech

Nameless said:


> A... gang valve? Alright, no biggy. I don't mind spending money for my pets ^_^
> You make it sound expensive though, is it? Will this... Pinch (what on earth is that?) thing work until I can get the money to buy one if it is expensive?
> 
> Also, how does a gang valve work? How is it assembled? Are there other supplies needed?
> 
> EDIT: Sorry for so many questions. I keep racing around the internet for the answers, but I can never seem to find them. And I don't have anyone who is experianced with fish that I can go and talk to.


Gang valves come in many different shapes and sizes, and prices, but for the most part they are all very cheap. Usually gang valves come assembled you just plug in the air hoses. You basically plug your air line(s) in and then you can control how much each out line gets, thats plugged in from outside the pump (if your pump doesnt have a built in flow adjustment). If your pump only has one air line and your not dividing it, you can just use the check valve type things with a flow control on it (forgot what they are called, but are only like 25 cents or something). Really there is tons of information on this stuff, even I have a site/channel covering some of this. The sites we ripped the earlier pictures/diagrams from is one of the best places to get aquatic information, and is usually one of the first links that always pops up on google, its very easy to find, if you try. 

Also it looks like you have your "sponge filter" running backwards, it looks more like a big airstone, from the way its setup. Even then there is barely any surface area on it, which is why yet again, when it comes to stuff like this I always suggest just spending the 5-10 bucks (which you spend on supplies anyways) on a commercial one (like ATI Hydro Sponges), because it just saves you the hassles, gives you better performance/surface area (most important thing), and will usually save you money anyways. Not to mention they just look way better when they are in the tank.


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## TheOldSalt

The air is supposed to exit the tube, NOT go through the sponge.


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## emc7

I can't tell from the pic if you have 2 tubes. You want the airline to go down inside to the bottom of the filter and you want a rigid upright for the water flow. You can use pvc or 3/8" or 1" rigid polystyrene tube they sell at store as UG filter replacement parts. Its okay to run the air in down the middle of the water tube or have it enter through a hole at the bottom,


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## Nameless

Alright, so I went today and got a gang vavle (Waaay inexpensive, I was so surprised) and the rubber band is no longer on there. I'd take a better picture, but I don't want to take it out of the bowl and have water fizzing out everywhere.

It is just the one tube, the one connected to the air pump.










I don't know if you can tell (because I surely can't, just by looking at the picture), but now the top is free of the band and the bubbles are coming out of the top of the opening.

I just... Alright, I am not at all mechanical or fish savvy. Is it supposed to work like convection does? You know, the warm air/water/magma surges up through the center and the cooler stuff travels downward on the sides and then back into the center source. Is the motion of the bubbles making it work sort of like that? Only without the change in temperature...


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## emc7

I think so, the bubbles rise up and pull the surrounding water with them, more water comes in to fill the space. You could watch the flow with food color (i'd do it w/o fish).


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## Nameless

Huh, Okay I might try that. So if that is the case, wouldn't I need the space in between the filter sponge and the top of the bowl for free bubble flow? Or would having the plastic pipe thing making the journey shorter be better?

It seems I will be doing experiments soon...


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## AquariumTech

Nameless said:


> I just... Alright, I am not at all mechanical or fish savvy. Is it supposed to work like convection does? You know, the warm air/water/magma surges up through the center and the cooler stuff travels downward on the sides and then back into the center source. Is the motion of the bubbles making it work sort of like that? Only without the change in temperature...


No, The pictures that were posted above show how it is supposed to work. Ill explain it again, because I am nice. The sponge is underwater, so there is water pressure on it at all times, in all places. So what happens is the air delivery system shoots air into the middle of the sponge, this creates an absence of water behind the sponge (in the middle if designed correctly). So since it is underwater, under pressure, this creates a vacuum, and the water replaces its self in the filter by passing through the sponge, to get to where that absence of water is, that is created by the bubbles/air. Of course this is with proper design, and powered operation. 

So when the water passes through the sponge it picks out debris and circulates fish waste products through it helping to grow your biological filtration. Which is also why different types of sponge material and densities have different effects.


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## AquariumTech

Nameless said:


> Huh, Okay I might try that. So if that is the case, wouldn't I need the space in between the filter sponge and the top of the bowl for free bubble flow? Or would having the plastic pipe thing making the journey shorter be better?
> 
> It seems I will be doing experiments soon...


Im/we're telling you man, you just have a big air stone sitting there. Its not a sponge filter. You might be able to turn it into a sponge filter with time and frustration (and most likely more supplies), but for a tank that size you can seriously get a nice sponge filter for like 2 bucks at a LFS.


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