# SPONGE FILTERS: Why and How



## waterdog

WHAT IS A SPONGE FILTER?

Sponge filters are a staple among aquarium keeps that need a low flow way to filter tanks with delicate residents. Sponge filters are the best alternative for not only betta keepers, but also for new born fry and shrimp. They help provide stable water conditions without a strong intake which can damage delicate fins, or even suck small new born fry into a filtering system that would kill them. They are economical due to the fact they can be cleaned and reused instead of having to replace filter media. They come in a variety of sizes and can be purchased for next to nothing. About the only down side (in some cases) to using them is they are driven by air pumps which, depending on the brand and surface they sit on, can be louder than a HOB (hang on back) filter. Also they take up room inside the tank and thus are more visible than a HOB.

THE FILTER AND ITS FUNCTION
Sponge filters can come in an almost infinite variety of shapes and sizes, commercially produced or home made. Its main use is not to remove waste from the water (although it does do that) but is to provide a place for beneficial bacteria to grow. The larger the volume of water, the bigger the sponge needs to be to provide enough surface area for more bacteria. Some filters will have odd shapes or shallow channels. This is to maximize the amount of surface area for bacteria to grow.

HOW DOES IT WORK?
A sponge filter will consist of three basic parts; 1) a sponge 2) a tube rising up from the middle 3) an air line supplied by an outside air pump.
The airline is inserted in the tube. As air bubbles rise, they push out water, creating a void. At the bottom of the tube are holes under the sponge which allow water to enter to fill the void. Once beneficial bacteria have colonized the sponge, the water flowing into the sponge is then cleaned. Pretty simple huh?

MAINTENANCE
Depending on the size of the tank and its bio-load (i.e. how many fish), which in this case we are usually talking about one betta, you will need to clean the filter about once a month. To do this, first you want to get a container and put some tank water in it. This is usually best done during water changes. (NEVER use tap or new water as this will kill your marvelous bacteria colony you have waited so patiently to grow.) Remove the air line and tubing from the sponge. Place the sponge in the container of tank water and gently squeeze a few times. Replace the tube and air line and reset into tank. (Yes it’s that easy) 
Q; How long will it last?
A; Depending on the material it should last for several years
Q; How often should I replace the sponge?
A; Not until the sponge starts falling apart when you squeeze it out! If you replace the sponge you will have to wait for a whole new bacteria colony to grow in the new one.

DIY SPONGE FILTER
Even though sponge filters are inexpensive, some of us just can’t resist the chance to say we made our own equipment. Sponge filters are the easiest thing you will ever make for an aquarium. (I designed and made my 35 gallon sump, so I know of which I speak) 
Materials needed;
Sponge (make sure it is NOT an antibacterial sponge. Kinda defeats our purpose)
I use a car wash sponge from the dollar store shaped like a figure 8. They are stiff 
enough to cut easy but soft when wet to allow water flow.
A plastic or pvc tube 1 inch diameter or less
Air tubing and air pump.
An inline valve or gang valve
A weight of some inert material such as slate to make a weight for the bottom (in small tanks, say 2.5 gallon, some people will put some gravel from the substrate to hold it down instead of weighting it)

First cut the filter. Depending on the size of tank is how big to cut it. Examples would be; for a 2.5 gal. you can cut one 2.5” in diameter X 3” high. In a 10 gal. you can do 3.5” diameter X 6” high. These are only starting reference points.
Next, cut the tube so that you have no less than 3” from tip to water surface.
Now put your cut sponge next to the tube and mark where, with the tube fully inserted, the filter sponge will come up to. Drill hole all the way through both sides, alternating sides as you go up to your mark.
CAREFULLY drill a hole in the center of the sponge slightly smaller than the tube.
If you are using a weight, affix the end of the tube with the holes you drilled to the weight. I use aquarium silicone for this. Let dry.
Now slide your sponge over the tube and push to the bottom. Make sure all the holes you drilled are covered.
Place the filter in your tank and squeeze so all the air goes out. Let rest on bottom.
Cut a place in air line to insert the valve.
Insert the airline all the way down the tube. Turn on air supply.
Adjust air flow so you have a steady flow of bubbles but soft enough so that the surface is not disturbed too much.

Be it factory made or DIY, you can now enjoy a cycled tank that will give your betta water quality he deserves no matter what size tank he is in, and cut down on his stress and yours with fewer large water changes.


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## Tikibirds

I vote for a sticky for this :-D


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## waterdog

Thank you Tiki for the vote!


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## MattsBettas

Sticky please!


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## ILLBETHEJUDGE

Really good information. Thanks.


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## waterdog

Thank you matt and ILLBE


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## PaulO

+1 to sticky vote

When I first started I didn't know jack about the options of equipment fish keepers have, and this is really one of the most underrated pieces of equipment even though they are very useful and less likely to break (less parts). Not to mention they probably aerate water more than a regular hob, internal, or canister filter.


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## waterdog

Thanks for the vote PaulO!!!!!


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## Laki

+1 to sticky. 
I had a rough time finding a good tutorial for a sponge DIY for my shrimp tank. This is great


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## babystarz

Yes, please sticky! Too many people get HOB filters for their bettas and end up with shredded fins, or even worse, dead fish. This seems to happen over and over again and I think we should all be nudging people to get sponge filters. They are superior in safety.


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## shawnee

cant belive u took the time to type this 0.o


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## efg321

Great Info.....should be required reading!


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## Hallyx

Good job, Waterdog.

Two things to keep in mind when considering sponge filters:

As the bubbles pop at the water surface a gas exchange takes place which adds oxygen to the water. This is important for the health of the nitrifying bacteria and stock. Betta and Gourami don't care about this.

However, this gas exchange also drives out CO2. This tends to raise the pH level--- more or less depending on water hardness. If your water is hard and your pH is already high, this is something to consider.

Sponge filters are not calculated to enhance the beauty of your aquarium.

And two tips:

Wrap the often-noisy airpump in a towel, then hang it on the wall. This is as quiet as I could get mine.

If your pump is below the surface level of your tank, a one-way check valve will prevent back-siphoning if your power goes out.


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## Laki

I don't know, my air pump is perfectly quiet. It makes less noise than my laptop cooling fan while being perched on top of my betta tank (the air tube is stretched across my desk to the other tank). 
Interesting point you made about the gas exchange Hallyx!! I know the disruption at the surface of the water caused my old VT to nip his fins bc he couldn't bubbles.


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## waterdog

Thank you all for your comments and sticky votes!!!! :-D




Laki said:


> Interesting point you made about the gas exchange Hallyx!! I know the disruption at the surface of the water caused my old VT to nip his fins bc he couldn't bubbles.


I have sponge filters in 3 betta tanks, a 2.5, a 5, and 2 in my 10 gallon and I have had no problems with either my fish or plant growth. As long as plants get the right light and regular water changes to replinish minerals in the water, they usually do fine. My 75 turns over water at the rate of 10 times per hour and it's like a jungle in there that I have to constantly trim back.

This is a picture of one of the two homemade sponge filters in my 10 gallon. I put two as I plan on dividing the tank soon.


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## Laki

They're nice!! (I was referring to the bubbles coming up out of those pvc tubes) at least in my old 1g tank it upset my fish. But in hindsight, the tank was too small and not enough plant cover.


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## Option

I know most breeder tanks do not use filtration of any sorts when the male betta is making its bubblenest but does anyone here actually use these in their breeding tanks? It's perfect for not sucking up the eggs nor fry. But do you find that the bubbles it creates is too turbulent for the bubblenest that the male bettas need?


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## OrangeAugust

Sticky, please!!


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## waterdog

Laki said:


> They're nice!! (I was referring to the bubbles coming up out of those pvc tubes) at least in my old 1g tank it upset my fish. But in hindsight, the tank was too small and not enough plant cover.


I agree that a 1 gal might be too small for any filtration. The smallest tank I have is 2.5 and no problems to report!

This is it's owner.....


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## waterdog

Thank you all for the compliments and sticky votes!!!!!!!!!!




Option said:


> I know most breeder tanks do not use filtration of any sorts when the male betta is making its bubblenest but does anyone here actually use these in their breeding tanks? It's perfect for not sucking up the eggs nor fry. But do you find that the bubbles it creates is too turbulent for the bubblenest that the male bettas need?


I am not a breeder and have no intentions of being one for awhile. I'm sure someone here that does breed can answer better than I can. I would think you could just shut off the air supply during spawning, then reopen after the hatch, but that is just a guess. :roll:


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## Hallyx

Putting a a piece of open cell filter sponge at the surface to catch the bubbles cuts down on surface turbulence. 

Using an airstone on the bottom of your airfeed tube creates smaller bubbles and more of them. This cuts turbulence and is also more efficient,


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## shawnee

sticky


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## Chevko

Fantastic little gem of information! I do hope they they make this a sticky as this is has awesome information, plus the images on the original post gives an idea as to what to look for for filters. One website I was peeking through I wasn't sure what kind of sponge filter to get and almost just totally ignored them altogether. Good thing I haven't bought one yet!


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## waterdog

I guess my article wasn't deemed worthy of becoming a sticky. 

I just want to thank everyone that voted for it to be a sticky and for all the great comments! I had fun talking about it.


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## breezywillow

Thinking about doing a DIY for my 2 gal tank, doing 2-50% and 1-100% water changes a week, what should I cut down to if I have a sponge filter or should I keep the water changes the same and just clean the sponge once a month?


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## waterdog

In my 2.5 with a sponge filter I simply do one 50% change a week and have no problems at all!


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## breezywillow

Thanks waterdog, your post was recommended by another member and has been really helpful in deciding on a DIY sponge filter, I agree with everyone else, this SHOULD be a sticky!!!


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## logisticsguy

waterdog said:


> In my 2.5 with a sponge filter I simply do one 50% change a week and have no problems at all!


We did a complete change from HOB to sponge filters last year on all tanks less than 10g. It was getting ridiculous the flow issues and breakdowns from the small HOBs. On larger tanks its good to have one of each in the tank as they can back each other up. The older the sponge the better and using the big tank to season up new sponge filters work well IME. Also a nice little trick is to take a pill bottle, fill it with media like Seachem Matrix, poke a couple holes in it and find a spot in the tank for it like inside a decoration or even attaching java moss to the bottle. It becomes an ammonia buster and can help keep a cycle stable.


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## waterdog

logisticsguy said:


> Also a nice little trick is to take a pill bottle, fill it with media like Seachem Matrix, poke a couple holes in it and find a spot in the tank for it like inside a decoration or even attaching java moss to the bottle. It becomes an ammonia buster and can help keep a cycle stable.


I like that idea!


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## Sparrowhawk

I agree that this should be a sticky! Wonderful thread!


A quick question though. I ordered a few sponge filters online (they were a couple of bucks each, less than the sponges at the cheapo store, haha!) and ordered two different sizes because I wasn't sure which would be best (the measurements were vague, it was eBay after all). Now they've arrived, one kind is teeny tiny, the other is massive in comparison to my 3.9gal tanks! Which of these would you recommend for a tank of that size (which will decrease in capacity slightly with the addition of gravel and more plants/hardscape)?

Small: 2.25" x 2"
Medium: 3.5" x 4.5"

That's not including the weighted bases and tube, just the sponge measurements. If I were to use the larger one, I'd have to saw some of the tube off, and sand it down smooth for it to fit under the water surface...

I wouldn't want to not have a large enough unit in the tank, it'd defeat the purpose of having one in the first place, but wow, is the "medium" big for where it'd be going! Heh.


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## Chevko

While this thread is going I wanted to throw you guys a question...

So, I didn't do full research like an idiot when I was filter hunting. I got my filter alright and it's exactly the one I wanted but... for some reason I thought it would come fully equipped. Uh. No. Silly me. What air pump or air stone system thingie would you guys recommend for me to use with this? It's a Hydro I. I have utterly no experience when it comes to pumps and the like. I only have better ideas with power filters over these weird thingamajigs.


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## Hallyx

The Tetra Whisper pump is cheap and as quiet as they get at that price....especially if you wrap it in a towel and hang it.

Silicon airline tubing is easier to work with than neoprene and just a few cents more.

I use a 1" long airstone. The Hydro is nice because you can install the airstone easily. Splice it under the airline base with a small section of tubing.

A larger filter is always better than a smaller one. It can grow a suitable colony faster. I know they're ugly, but...

You can also use a mat of Java moss at the surface to catch bubbles and cut down surface ripples. Makes a flow-adjuster unnecessary.


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## waterdog

Sparrowhawk said:


> I agree that this should be a sticky! Wonderful thread!
> 
> 
> A quick question though. I ordered a few sponge filters online (they were a couple of bucks each, less than the sponges at the cheapo store, haha!) and ordered two different sizes because I wasn't sure which would be best (the measurements were vague, it was eBay after all). Now they've arrived, one kind is teeny tiny, the other is massive in comparison to my 3.9gal tanks! Which of these would you recommend for a tank of that size (which will decrease in capacity slightly with the addition of gravel and more plants/hardscape)?
> 
> Small: 2.25" x 2"
> Medium: 3.5" x 4.5"
> 
> That's not including the weighted bases and tube, just the sponge measurements. If I were to use the larger one, I'd have to saw some of the tube off, and sand it down smooth for it to fit under the water surface...
> 
> I wouldn't want to not have a large enough unit in the tank, it'd defeat the purpose of having one in the first place, but wow, is the "medium" big for where it'd be going! Heh.


The smaller one would be fine for the tank your putting it in as long as the only resident of the tank is 1 betta. 
An example of how this works is simple. The BB colony is supported by how much ammonia is in the water. The more fish creates a larger 'bio-load' which needs more BB to handle it. On the other hand, if you have 1 fish, your bio-load is smaller and requires less BB.
If you had a tank with say 10 fish and you took 9 out, some of your BB would actually die off as there is not enough ammonia to feed it all. You can't have more BB than ammonia to support it. Natures checks and balances system is pretty effecient!


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## waterdog

Chevko said:


> While this thread is going I wanted to throw you guys a question...
> 
> So, I didn't do full research like an idiot when I was filter hunting. I got my filter alright and it's exactly the one I wanted but... for some reason I thought it would come fully equipped. Uh. No. Silly me. What air pump or air stone system thingie would you guys recommend for me to use with this? It's a Hydro I. I have utterly no experience when it comes to pumps and the like. I only have better ideas with power filters over these weird thingamajigs.


I'll defer to Hallyx on this one as I really have yet to find an air pump that I am crazy about. So far, to me, one is pretty much the same as the next.
I do agree silicone tubing is ALOT better than the cheaper plastic tubing. For the pennies difference it's definately worth it!


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## Chevko

*@Hallyx & waterdog*
Thanks so much on the tips! Would you suggest then PetCo's brand of tubing? It's more expensive than the tubing from PetSmart. /shot

*@Hallyx*
I went with the smaller one for size, rather than appearance. I keep putting the tank so much smaller in my mind that this one I feel most comfortable with. I'll probably wind up upgrading it after a period, but until then... Plus it took me ages to find a place that sold the I version and not for too bad a price, even with shipping included. I will definitely keep the moss in mind, too :3 Hoping to establish plants before I get the fish put in.


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## waterdog

Chevko said:


> *@Hallyx & waterdog*
> Thanks so much on the tips! Would you suggest then PetCo's brand of tubing? It's more expensive than the tubing from PetSmart. /shot
> .


Both places sell silicone tubing, but I do prefer the petco brand


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## Sparrowhawk

waterdog said:


> The smaller one would be fine for the tank your putting it in as long as the only resident of the tank is 1 betta.
> An example of how this works is simple. The BB colony is supported by how much ammonia is in the water. The more fish creates a larger 'bio-load' which needs more BB to handle it. On the other hand, if you have 1 fish, your bio-load is smaller and requires less BB.
> If you had a tank with say 10 fish and you took 9 out, some of your BB would actually die off as there is not enough ammonia to feed it all. You can't have more BB than ammonia to support it. Natures checks and balances system is pretty effecient!


Thank you for the response!
:-D


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## Vizja13

Sticky vote! I've been looking for a DIY guide. <3 thank you!


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## waterdog

Vizja13 said:


> Sticky vote! I've been looking for a DIY guide. <3 thank you!


Thank you for the vote Vizja, but I have given up hope of this ever becoming a sticky. Guess I am not worthy. :crazy:


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## Chevko

omg. So. I have my airpump, my hose and my filter. I was wanting to ask you guys, after looking at the end result image in the first post if I had this put together right.

I have the hose connected to the, er, hose... connector... male part on the filter with the tube around it. Other end is connected to the pump. Did I do this right? D: I'm nervous that this won't go properly and don't want to fill the tank and turn it on to see. It seems fool-proof, but... eheh. be my luck...


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## Hallyx

That sounds right. You can try it out in a deep bowl. As long as the "lift" tube (that the bubbles climb up) is completely submerged, it will work.


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## LoriKeet

Sticky vote.


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## waterdog

A picture would be helpful but sounds right. These filters are really easy. Don't make it hard on yourself!


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## Chevko

*@Hallyx & waterdog*
I'm not sure where my camera is, but it's a straight shot with the tubing connected to the air pump, Tetra Whisper 10 (or should I have gotten 20?), and through the rigid tubing to connect to the male part on the filter. It just seems way too easy to be true is the thing, lol.


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## Hallyx

Chevko said:


> It just seems way too easy to be true is the thing, lol.


Silly, isn't it? OK you can make it more complicated by putting in an adjustable air-flow restricter valve instead of capping the lift tube with Java moss or foam. Costs about 3 bucks.

If your pump is located next to or lower than your tank, you probably should install a one-way valve in the airline to prevent reverse siphoning back into the airpump if your power goes out. Or you can hang the pump on the wall higher than your water level. That'll fix it.

Fitting an airstone at the air outlet makes smaller bubbles. That's a good thing

Sorry, can't think of any more ways to make it more complicated.


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## LittleBettaFish

That's why I love sponge filters. I run around 15 off the one pump and all I need to add is some valves and some airline tubing. So much easier having a filter that you can turn down to one or two bubbles every second without needing to have to mess around with baffles and spraybars.


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## waterdog

Easy is a good thing! I know it seems like anything to do with 'proper' fish keeping should be complex and expensive, and sometimes it is, but this is one of those rare times when simple works. Put an air control valve inline then sit back and enjoy!


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## acitydweller

this should be a staple for every type of aquatic tank


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## Chevko

Hallyx said:


> Silly, isn't it? OK you can make it more complicated by putting in an adjustable air-flow restricter valve instead of capping the lift tube with Java moss or foam. Costs about 3 bucks.
> 
> If your pump is located next to or lower than your tank, you probably should install a one-way valve in the airline to prevent reverse siphoning back into the airpump if your power goes out. Or you can hang the pump on the wall higher than your water level. That'll fix it.
> 
> Fitting an airstone at the air outlet makes smaller bubbles. That's a good thing
> 
> Sorry, can't think of any more ways to make it more complicated.



My filter came with a valve, double headed, so I think it wouldn't be a good idea to have it on there =\ as I don't have anything to connect the second line to. And I haven't had this run just yet since I don't yet have anything big enough to test it out in. Or did you mean one-way in that it's a direct line to the pump?


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## LittleBettaFish

You can get valves that control the flow of the water. So you have your airline tubing that attaches to the pump, then the valve, and then the airline tubing that goes into your sponge filter. 

I'm not sure what they are called but they look like this

http://www.ebay.com/itm/5x-Aquarium-Air-Line-Tubing-Volume-Flow-Control-Valves-/260906104146

The check valve is to stop the water from back siphoning if your power goes off. I am naughty and don't use them though I am thinking of buying some as they are very cheap to purchase.


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## Chevko

Yeah, I have one of those, but it's a t-shaped one instead of like that. It came with the filter. I wasn't really certain about using it but I can clip off a piece of my tubing and put it on here. The existing tubing I've got connecting the two is a bit long because I was using it to draw more water out of the tank before I moved it. Is there a length to keep in mind with the tubing? Should it be only so long without much slack? I just thought of this with the mention of backflow.


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## waterdog

The only effect tubing length has is the longer it is the less pressure you get. I am assuming from your valve description that you have a double gang valve? You can use it without opening both valves. I just use the cheap inline valves since I only have 1 filter per tank and they are too far apart to run more than one filter on the same pump.


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## Hallyx

Was this brought up earlier in this thread?

The bubbles breaking at the surface promotes gas exchange and provides oxygen for the nitrifying bacteria. 

It also outgasses some CO2 which tends to raise the pH.

Hate to mention this so far down in this thread.


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## waterdog

I don't remember this being brought up Hallyx, but a point anyway.


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## finnfinnfriend

Would this be enough for about 5 gallons of water, no live plants, and one betta with no tank mates?http://www.kensfish.com/moreinfo/ati-sponge-filter-mini.html


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## waterdog

Perfect! Just remember to put a control valve on your airline so you can control the air flow.


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## finnfinnfriend

waterdog said:


> Perfect! Just remember to put a control valve on your airline so you can control the air flow.


Okay so 2.75in diameter by 2in high sponge will be enough? How do you install a control valve?


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## waterdog

Depends which you get, inline or a hob gang valve. I use the inline type. Simply cut the air tubing about 6 inches from the pump and insert into each end of the valve. When you start the pump watch the bubbles. You want them to make just a slight ripple on the surface without churning the surface. Play with it. It's easy!


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## finnfinnfriend

waterdog said:


> Depends which you get, inline or a hob gang valve. I use the inline type. Simply cut the air tubing about 6 inches from the pump and insert into each end of the valve. When you start the pump watch the bubbles. You want them to make just a slight ripple on the surface without churning the surface. Play with it. It's easy!


Awesome! Thank you so much! So just to be completely sure, the hydro sponge mini thats rated for up to 7 gallons that I linked to, that is 2.75in wide x 2in tall should be big enough for my 5 gallon single betta tank that does NOT have any live plants?

Im sorry, I have really strong OCD tendencies


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## finnfinnfriend

Oh yeah and the lift tube has a 1in diameter so I guess there is a 1in wide hole through the sponge.


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## Juditko

This is an excellent thread...STICKY!

I found this YouTube video to be extremely helpful...(NOT to advertise for this particular brand of sponge, though it is what I purchased):
http://www.youtube.com/watch?v=V2_QKq3_YsI

It looked complicated before I bought it, but it's not. And mine actually came totally assembled. For use with an airstone, attach a 1/2 to 1 inch piece of airline below the bullseye assembly and attach a cylindrical airstone to it. Then attach the airline to the pump on the top side of the bullseye. (The top side connection is shown at 2:20 in the video.) 

I mention a cylindrical airstone as that is what is most likely to fit. Hallyx and Callistra taught me how to connect mine when it came in!

I have one suggestion...could someone who has the capability include photos here of the different effects achieved with the lift tube cut at well under the water, at the surface, and above the surface? Some members have been trying to help me understand what the different heights will do. Mine is at surface currently and I'm thinking of cutting it down about an inch below. I was hoping to get a height that would keep the filter from "spitting" mist all over the underside of the lid. I might try the java moss suggestion if I can find some at my local store...Got to get the back-flow protector valve also...

I have a Tetra whisper airpump and it is super-quiet...

I'm a newbie at this, but if you're new, too, rest assured, it is MUCH easier than it looks. I should have bought this type first!!


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## waterdog

finnfinnfriend said:


> Awesome! Thank you so much! So just to be completely sure, the hydro sponge mini thats rated for up to 7 gallons that I linked to, that is 2.75in wide x 2in tall should be big enough for my 5 gallon single betta tank that does NOT have any live plants?
> 
> Im sorry, I have really strong OCD tendencies


It will be fine. It goes by tank volume. The amount of live plants or the lack of live plants has no bearing on sponge size needed.




Juditko said:


> This is an excellent thread...STICKY!
> 
> 
> I have one suggestion...could someone who has the capability include photos here of the different effects achieved with the lift tube cut at well under the water, at the surface, and above the surface? Some members have been trying to help me understand what the different heights will do.


If you read my initial article, I advise having the top of the lift tube no less than 3 inches from the top of the water. You really shouldn't bypass this step. The lift tube is what makes a sponge filter work. The air pushing water out is what makes it draw water through the sponge. If your getting 'splattering' it means you have too strong of an air flow, thus the reason for the control valve. Slow down the air flow until you just have a gentle 'ripple' effect on the surface.

Sponge filters, IMO, are the easiest way to filter a betta tank. Simple and effective. No need to try to reinvent the wheel! :thumbsup:


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## finnfinnfriend

Does it matter where I put the air pump?


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## waterdog

finnfinnfriend said:


> Does it matter where I put the air pump?


Not really. Just remember the longer the air tube the less pressure you get, so I wouldn't put the pump in another room. lol:demented:


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## MiyuMikaelson

Opinions on this:








Topfin Filter 10 with:









Does this work well enough? It's slowed down my water-flow without making the water absolutely still.


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## finnfinnfriend

waterdog said:


> Not really. Just remeber the longer the air tube the less pressure you get, so I wouldn't put the pump in another room. lol:demented:


Alright. Thanks for the help!

STICKY!


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## waterdog

MiyuMikaelson said:


> Opinions on this:
> 
> Does this work well enough? It's slowed down my water-flow without making the water absolutely still.


If it works for you then it is fine. That is a HOB, the pre-filter doesn't make it a sponge filter per-say. Depending on the size of tank and the situation determines if the HOB or a true sponge filter is what's needed. Example, you wouldn't put that on a 2.5 gallon or even a 5 gallon as it would make too much outflow. Personally I have a spilt 10 gallon with a sponge filter on each side to ensure both sides get maximum filtration without too much turbulance.


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## MiyuMikaelson

waterdog said:


> If it works for you then it is fine. That is a HOB, the pre-filter doesn't make it a sponge filter per-say. Depending on the size of tank and the situation determines if the HOB or a true sponge filter is what's needed. Example, you wouldn't put that on a 2.5 gallon or even a 5 gallon as it would make too much outflow. Personally I have a spilt 10 gallon with a sponge filter on each side to ensure both sides get maximum filtration without too much turbulance.


Ah, my tank came with this filter; it's a 5 Gallon. I bought the pre-filter to help slow it down. (And make it potentially shrimp safe.) I've also "ghetto rigged it" with part of a plastic soda bottle so that the water distribution coming out is slowed and more "equal" in distribution and wont cause him to topple over. It's not quite ideal, but I'm trying to make it work.
^^;


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## waterdog

Your betta will let you know if it works or not. You have pre-filtered so his tail doesn't get sucked up, you've baffled the outflow. About all you can do. Keep an eye on him and watch to see if he looks tired from fighting current. Usually they will either hide behind the outflow of the pump to escape current, or just lay on the bottom from being exhausted.

Just curious.........is this setup for the fish in your avatar?


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## MiyuMikaelson

waterdog said:


> Your betta will let you know if it works or not. You have pre-filtered so his tail doesn't get sucked up, you've baffled the outflow. About all you can do. Keep an eye on him and watch to see if he looks tired from fighting current. Usually they will either hide behind the outflow of the pump to escape current, or just lay on the bottom from being exhausted.
> 
> Just curious.........is this setup for the fish in your avatar?


Yes it's for him, he's got some long fins, which is why I've been doing everything I can to slow the water flow.
^^;

I will definitely keep a close eye on him and make sure everything is alright and that he's not becoming more exhausted.


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## finnfinnfriend

So sponge filters really make alot less current than HOBs, huh?


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## waterdog

It's not even a contest. Sponge filters, especially with the air control valve, make a lot less water disturbance.


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## finnfinnfriend

Could I just have a longer airline tube instead?


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## waterdog

You could, just have to play with it a bit to determine the right length to get the air flow you want.


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## LittleBettaFish

Why don't you want to use a valve? I use them on most of my sponge filters as I have fry in tanks and I can get the flow down to only 1-2 bubbles a second. 

It sounds like it is going to be more effort to try and get the flow down by just extending the airline tubing. You could use an air pump that is underrated for the size sponge filter/tank but this could end up burning it out. 

Valves are like 40c here and easy as to put in.


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## logisticsguy

Those Fluval pre filters are terrific for HOBs. They not only do they prevent getting sucked up but catch a ton of muck before it hits the HOB and are just gummy with bb. I have one on every HOB I have left. Sponge filters are vastly under used by betta keepers imo. So simple cheap and easy to clean. In my opinion they offer better mechanical filtration and last a very long time.


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## waterdog

logisticsguy said:


> Sponge filters are vastly under used by betta keepers imo. So simple cheap and easy to clean. In my opinion they offer better mechanical filtration and last a very long time.


Exactly the reason I started all this. Since, for whatever reason, sponge filters are not sold in most larger fish stores, I figured that there was a lack of information out there so people could make informed choices, especially with Bettas!


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## finnfinnfriend

I do want to use a valve, I was just asking


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## MooseKnocker

What would be the best sponge for a 2.5 gal?


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## Sparrowhawk

LittleBettaFish said:


> Why don't you want to use a valve? I use them on most of my sponge filters as I have fry in tanks and I can get the flow down to only 1-2 bubbles a second.


Ah! This reminds me of a question I had ages ago but forgot to ask! How does the flow of bubbles affect filtration? Are more bubbles better, or is it just a matter of preference? I'm still fairly clueless on this particular topic and hanging on every word in this thread pretty much. Learning is good, heh. ^.^


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## waterdog

MooseKnocker said:


> What would be the best sponge for a 2.5 gal?


In a 2.5 I like the flat sponge the best. It takes up almost no room and is easily hidden. If you look in my picture album in 'My Tanks' you will see a closeup of the one in my 2.5


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## waterdog

Sparrowhawk said:


> Ah! This reminds me of a question I had ages ago but forgot to ask! How does the flow of bubbles affect filtration? Are more bubbles better, or is it just a matter of preference? I'm still fairly clueless on this particular topic and hanging on every word in this thread pretty much. Learning is good, heh. ^.^


In theory the more bubbles the faster the flow through the sponge. Just remember you don't want so much that you churn the surface. You should adjust it so you just have a gentle ripple on the surface.


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## Sparrowhawk

waterdog said:


> In theory the more bubbles the faster the flow through the sponge. Just remember you don't want so much that you churn the surface. You should adjust it so you just have a gentle ripple on the surface.


A gentle ripple on the whole surface area (talking a small tank, 3-4 gal) or just the area around the filter? Thanks for being patient with me, just like to clarify everything to make sure I'm understanding correctly. >.<


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## waterdog

Around the filter area


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## Sparrowhawk

waterdog said:


> Around the filter area


Cool, thanks.


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## Juditko

Thanks, sparrow hawk. I'm watching and learning also.


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## Hallyx

As Waterdog says, smaller bubbles are more efficient; they move more water for any given airflow. You can or should only turn down the flow so much. Too slow and it's not filtering much at all. 

If you've got it adjusted to just ripple the surface, rather than turn down the flow (and diminish the filtration) you're probably better off putting a flat open sponge above the lift tube to catch the bubbles and smooth the flow. Juditko will tell us how that pre-filter sponge works over time. Java moss is as good and I like the way it looks.

If you're curious, you can actually determine the flowrate by holding the filter at an angle and letting it flow into another container. Time it and measure it. ATI Hydro explains how to do this. That will be the minimum flow you can expect at that setting.

If the surface is rippling, that's an adequate flow rate for me.

A sponge filter bio-filters well, with less flow than a typical HOB, because it uses a relatively larger foam block for housing nitrifying bacteria. A good HOB can be a better mechanical filter. Many serious keepers use both.


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## Perry the platypus

I can message a Mod to make this a sticky!


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## Juditko

Great idea, Perry!


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## waterdog

If you would like to see a video of a sponge filter working, click this link: http://www.youtube.com/watch?v=F_7jnfYrhss

Special thanks to finnfinnfriend for supplying the video and link! :yourock:


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## finnfinnfriend

This thread really should be a sticky. Sponge filters are a great option for people looking to have a cycled betta tank...


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## royal

+1 to the sticky! Awesome thread! I was wondering if you could infact make your own sponge filter.


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## finnfinnfriend

How many sticky votes does a thread need? Most threads like this would have been stickied days ago...


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## waterdog

royal said:


> +1 to the sticky! Awesome thread! I was wondering if you could infact make your own sponge filter.


If you read my original article on this thread you will see half of it is how to DIY


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## heckofagator

Where can you buy the flatter sponge filter that would be ok for smaller tanks? I can't seem to find it anywhere.

Also, is the smallest Tetra Whisper pump recommended for a tank of this size?


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## waterdog

heckofagator said:


> Where can you buy the flatter sponge filter that would be ok for smaller tanks? I can't seem to find it anywhere.
> 
> Also, is the smallest Tetra Whisper pump recommended for a tank of this size?


Easiest (and cheapest) place to get them is on ebay.
I've also found them here; http://www.petstore.com/lees-pet-pr...m_campaign=mdcseshopping2&utm_content=LE13396


I really don't recommend power filters for anything less than 5 gallons.


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## heckofagator

Thanks. Got it. So square sponge filter, air pump and air line tubing? Anything else I'd need to order to get this set up and working?


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## waterdog

I always recommend an inline air control valve so you can set the bubble rate to not get too much surface aggitation.


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## heckofagator

I found the Lee filters on Amazon, so that's good. Can be here in a couple of days with free shipping.

For the inline valve, is this what I want? Also, I think I'm going to go with the triangle version. Seems this would best fit in the corner of the tank? I'm really worried this thing is going to be HUGE in a 2.5g tank.


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## waterdog

That valve will be great.
If you are worried, look in my photo album at my 2.5 with the round version of that filter. You can hardly see it!


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## heckofagator

I think I'm going to have to go to plan B.

I couldn't believe the size of this filter when I opened the box from Amazon. My wife was right there and I knew she was right.

Her: what's that?
Me: the fitler
Her: the filter for WHAT?
Me: the tank?
both of us: hahahaha, yeah, no way

This is like 10 times bigger than I was expecting and will probably take 1/3 of the tank. In fact, I don't think it'd even fit front to back. If it would, it'd be pushing up on both the front and back glass.


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## waterdog

That looks a lot bigger than a 5 gallon sponge. What size does the package says it's for? You can cut it smaller.


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## Blue Fish

So how much sponge do you need do you need for a 20 gallon tank? Is there a certain ratio of sponge to gallons?


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## waterdog

The average commercial filter for a 20 gallon is 4.5"D X 8.0"H


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## Blue Fish

Ahh, so these are pretty big measurements.  I'll get a carwash sponge today and get this started.  

I'll put it in lengthwise across the back and put some plants in front, then it won't be as obvious.  Thanks for the quick response and the information!!


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## logisticsguy

Im not crazy about the sponge quality of Lees. They are ok for sure but not the best jmho. I have started to baffle my sponge filters to see if I can make such little disturbance on the surface that my boys can make nests ect with the filter on. It also allows me to run the air pump faster than I did before. You can pick up these feeder rings from most lfs very cheap that are designed to float and attach to the tank. It has worked amazingly well for me.


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## avraptorhal

Thanks for the info!!


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## ollief9

I have one problem with these filters: noise. They are probably a great alternative to the usual internal power filters I use but, since all my tanks are in my bedroom, I would worry that the noise from the air pump and bubbles would keep me from falling asleep. Does anyone have any experience with this or know any quiet air pumps?


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## avraptorhal

I have two air pumps operating and they are quieter than two currently operating HOB filters. I discovered that the noise level is largely dependent on where the pump is located. If the pump is located on a cabinet or bookcase shelf the noise is magnified. I relocated the pumps to the floor under the shelves they had been on. That helped reduced the sound that I heard.

Placing the pumps on a sound absorbent pad (something like a kitchen sponge or a sheet of neoprene, bubble pack or the equivalent) on a shelf may also reduce the sound perceived.


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## ollief9

I have never had a HOB filter so I can't really make a comparison (I think internal power filters are much more common than HOBs in Europe because I have yet to see a HOB for sale in any pet stores here). I like the sound of DIY sponge filters so I will look into making one of those once I have bought an air pump. Perhaps a (very large) sponge filter could be used in a pond? My pond, even though it is filtered, is very murky and perhaps a sponge filter could help clear it up.


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## avraptorhal

Thanks for the info.

Question - Another site recommends that the top of water escape tube remain at least 3 inches from the water line. Do you know any reason for that?


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## waterdog

avraptorhal said:


> Thanks for the info.
> 
> Question - Another site recommends that the top of water escape tube remain at least 3 inches from the water line. Do you know any reason for that?


I wrote the same thing in my original article in this thread. It's to allow free flow of bubbles and water through the tube and out the top so you don't restrict water flow through the sponge.


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## justmel

Thank you waterdog for creating this thread & having it in you signature. That's how I found it & it's going to prove invaluable to me. I'm in the porcess of setting up 8 tank (3 divided for makes, a sorority, 2 spawning, & 2 grow out tanks) at least. I've never been clear what size sponge filter to get for my tanks (my LPS doesn't sell them). I have 1 sponge filter currently & it's twice the size I needed it to be, but it still works. This is going to save me a lot of money and headache trying to figure out what to get! Now I just need to find a DIY on tank dividers!


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## isochronism

I recently purchased a DeepBlue BioMaxx 10 hob power filter for my shrimp tank. 
I then found a Fluval Edge pre-filter sponge that slips on the intake. Small black cylindrical type.
Waterdog, a very excellent post!!!


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## waterdog

Your very welcome justme and isochronism and thank you for the kind words. This thread has been a great joy to me being able to help people with my limited expertise. Filtration has been an obcession of mine for years and is the one area I feel I can honestly help.


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## Jexx

I'm gonna go ahead and jump on the tank you bandwagon waterdog  I too found out about sponge filters through your thread and asked a million questions and am now very happy with mine. I don't feel I am ready to make my own but I am super happy buying them. I like that I can take mine and put it in a bigger tank and it will still work. I also like how low maintenance it is. Currently the only filter I haven't tried is a canister filter. For me I'd say its a close tie between the sponge filter and the internal filter but the internal filter requires much more upkeep.


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## ryancalif

Waterdog, I love the idea of building a sponge filter, but have some questions. Great information by the way!

1. What kind of porosity are you looking at for these sponges? You mention a car washing sponge in your first post, but most of them are pretty dense sponges as far as I know... Have you tried verifying how well these filters work with testing? A dye test might work well... squirting some dye near the outside of the filter to see if it gets sucked up.

2. Are you hollowing out the inside of the sponge at all to reduce the amount of sponge material the water needs to travel through? 

Thanks for the info!


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## waterdog

Thank you Jexx for the kind words. I am glad you are so happy with your new filters. Nothing wrong with buying them. Some of us are just too DIY for our own good! lol

Good questions ryan. While I have not done personal comparisons on sponge material, I have read extensively those who have. My take on it boils down to this.......
some argue course sponges do offer more surface area for BB. The downside is they tend to clog more easily due to material getting loged on the bigger cells. Smaller cells hold more material on the outside, thus keeping the water channels free. Also small cell sponges seem to last longer due to the fact they are less likely to be torn during cleaning. To compensate, commercial manufacturers sometimes cut the exterior in 'shapes' believing it makes more surface area.

IMO in the average betta tank there is not enough bio load, i.e. lots of fish, to warrant all this. The appropriate size sponge of any type should be more than enough for a single fish.


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## Nibblez

Great informative info here, was clueless as to what a sponge filter is as well as the hype about it. So would this actually be recommended over the HOB filters if you had a large tank? What sould be considered the ideal size or minimum size tank to use a sponge filter over a HOB unit? How about the filter units that sit in the tank, how do that compare to the spone filter?


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## Tikibirds

Do you know if there is a way to get a shorter lift tube? or is it easier to get a smaller filter?


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## waterdog

Nibblez said:


> So would this actually be recommended over the HOB filters if you had a large tank? What sould be considered the ideal size or minimum size tank to use a sponge filter over a HOB unit? How about the filter units that sit in the tank, how do that compare to the spone filter?


Filter type depends on the fish being kept. Some fish don't like a lot of water movement, aka bettas in small tanks, Discus in large tanks. In some larger setups you can actually use a sponge filter in addition to a power filter. Case in point, I use a sponge filter in addition to my HOB in my goldfish tank as it provides more biological filtration as goldfish produce a lot of waste and IMO the HOB doesn't have enough surface area to handle the load. The HOB powers out the solid waste and the sponge provides more BB. Seems to work well as a tag team as fancy goldfish should be allowed 10 gal per fish. I have 7 in a 40 gal and my water is crystal clear with only once a week WC.
Personally I am not a fan of in tank units.



Tikibirds said:


> Do you know if there is a way to get a shorter lift tube? or is it easier to get a smaller filter?


Smaller filter for sure. You could always cut the lift tube, but the problem with that is you reduce the amount of updraft therefore reducing the amount of water drawn through the sponge!


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## Nibblez

Sorry about all the typo, was rush typing in class. Just got myself a 10 gal for my betta, going NPT in that tank soon, still have to research about shrimps and snails. I have a HOB filter right now and i was thinking of just relying on that, would it be sufficient?


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## waterdog

Nibblez said:


> Just got myself a 10 gal for my betta, going NPT in that tank soon, still have to research about shrimps and snails. I have a HOB filter right now and i was thinking of just relying on that, would it be sufficient?


As long as it doesn't produce too much water flow you should be fine!


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## justmel

I'm getting ready to make a bunch of these up, at least 12. Can you help me with a couple measurements? What would you suggest for a 5 gallon tank & a 29 gallon tank? Does it matter what they are being used for (such as a 10 gallon being used for fry vs. a 10 gallon divided for 3 bettas)?


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## waterdog

*Dimension:*
*Size*
*Model #*
*Product Dimension*
*Max. Tank Size*
Small
XY-2835
2.0"D X 4.75"H
5 GAL
Medium
XY-180
3.0"D X 6.5"H
10 GAL
Large
XY-380
4.5"D X 8.0"H
20 GAL



This chart gives you an idea of size for various tanks.

In my 10 divided I made two the size of 5 gallon filters and put one on each side as you don't have a lot of water movement in a divided tank.


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## justmel

Thank you waterdog! I was just recently thinking that I might need to do things differently like that in my divided tanks. Glad to know for sure it probably is a better idea.


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## Chevko

I was curious... should one use carbon in sponge filters? or can we?


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## Tikibirds

They do make carbon based sponge filters but I have only seen them on ebay. 










IMO carbon is kinda pointless unless for some reason you need chemical filtration - like my snail tank needs carbon otherwise the water reeks to high heaven 24 hours after a water change. i am not willing to change the water every day. 
Not sure how well the carbon sponge would work because carbon only works for a month or so and then needs to be replaced. 

SInce i have money again, I plan on getting 2 sponge filters for the divided 10G so both sides get filtration and water movement. Does anybody now if these type of sponge filters are any good? They sell for ebay for pretty cheap









or should I just pay the extra few bucks and get the hydor sponge? The LPS has Deep blue sponges but they are all too big-for 30 gallon tanks and up.


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## SnowySurface

Tikibirds said:


> They do make carbon based sponge filters but I have only seen them on ebay.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> IMO carbon is kinda pointless unless for some reason you need chemical filtration - like my snail tank needs carbon otherwise the water reeks to high heaven 24 hours after a water change. i am not willing to change the water every day.
> Not sure how well the carbon sponge would work because carbon only works for a month or so and then needs to be replaced.
> 
> SInce i have money again, I plan on getting 2 sponge filters for the divided 10G so both sides get filtration and water movement. Does anybody now if these type of sponge filters are any good? They sell for ebay for pretty cheap
> 
> 
> 
> 
> 
> 
> 
> 
> 
> or should I just pay the extra few bucks and get the hydor sponge? The LPS has Deep blue sponges but they are all too big-for 30 gallon tanks and up.


I'm using the sponge filter in the second picture (that has two sponges) in my 5 gallon tank. It's a bit big, but works well for me so far. But I did have a bad algae bloom the first month I started using it. 

Oh, I probably should mention that my tank was already cycled with a HOB filter. So when I switched filters I left the filter insert in the tank for a few weeks to seed the sponge filter and (at least attempt to) avoid messing with my cycle. I don't know if that's part of the reason for my algae bloom.

So far, the "cheap" filter from eBay is holding my cycle just fine after 2 months.


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## waterdog

Carbon is not a huge issue in most betta only tanks since weekly water changes usually prevent the water from having an odor. It's not a bad thing to have and can certainly help to 'polish' the water sparkling clean.


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## Tikibirds

I don't mind the sponge being big but I am a little concerned that the tube thing will be too tall (have that issue with the one in my 20G). So I am thinking maybe these would be better?
http://www.ebay.com/itm/6x-XY-2835-...591292386?pt=Fish_Filters&hash=item53f4ea77e2

2 of those would be sufficent for a 10g? 
Filter Size: 2-1/8" X 2-3/4" (D*H)



> Quote:
> Originally Posted by *Tikibirds*
> _Do you know if there is a way to get a shorter lift tube? or is it easier to get a smaller filter?_
> 
> Smaller filter for sure. You could always cut the lift tube, but the problem with that is you reduce the amount of updraft therefore reducing the amount of water drawn through the sponge!


I should get a smaller filter but I would hate for this one to go to waste.


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## Bluelily54

Waterdog, I posted a question about filters a while back and I just wanted you to know I followed your advice about getting a sponge filter. I'm really happy with it, thanks for the great tip! =] No more torn fins and the water is just as clear, he even plays in the bubble stream coming from the top. =D


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## waterdog

I am so glad to hear it Bluelily! I hope that I am helping a few people enjoy their pets a little more. Makes me feel good to help!


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## waterdog

I see we have a whole new group of keepers joining the forum. I hope you find this thread helpful. I try to answer all questions as soon as possible!


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## Jexx

this thread was such a huge help to me when i was new and switching my filters around. this is good stuff waterdog


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## avraptorhal

Great info. I often wondered how the sponge filter worked.


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## waterdog

Thank you everyone!!!! Makes me feel good to know I helped!


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## Saphira101

This needs to be stickied!!!!


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## finnfinnfriend

What would you say is the minimum length the lift tube needs to be?


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## waterdog

finnfinnfriend said:


> What would you say is the minimum length the lift tube needs to be?


That really depends on how big the sponge is. The thicker the sponge, the more lift you need to create enough vacum to draw water through the sponge. For small sponges (like a 5 gallon) I would say 2 1/2 to 3 inches. I have a commercial made 20 gallon sponge in my 40 gallon goldfish tank (creating more BB in addition to the HOB. Goldfish produce a lot of waste) that has a 4 1/2 inch tube.


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## finnfinnfriend

waterdog said:


> That really depends on how big the sponge is. The thicker the sponge, the more lift you need to create enough vacum to draw water through the sponge. For small sponges (like a 5 gallon) I would say 2 1/2 to 3 inches. I have a commercial made 20 gallon sponge in my 40 gallon goldfish tank (creating more BB in addition to the HOB. Goldfish produce a lot of waste) that has a 4 1/2 inch tube.


Thank you!


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## hodad66

Thanks for this thread!! Great info for my Eheim 4 gallon


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## danbayne

AWESOME thread! I am new to Betta tanks (mistakenly thought bowls were ok) and am meticulously planning a planted 3g cube. Seriously, I was looking at Sponge Filters on Amazon just a few hours ago, because they popped up in my recommendations, and I had not a clue how to utilize them. Jumped to Bettafish.com, saw your Sig in a habitat thread and was thankful to reach this great discussion. THANK YOU.


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## hodad66

I just retrofitted my new tank because of this great thread!! My
pix and tank..... http://www.bettafish.com/showthread.php?t=217682


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## waterdog

Thank you danbayne and hodad! Makes me feel good I could help!


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## FirstBetta

Ditto for sticky.


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## FirstBetta

Sticky for Sponge filter description by Waterdog!


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## shannonpwns

If I have a sponge filter in my planted sorority, do I still need a HOB filter too?


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## millersrepairshop

Sticky please. Great info waterdog. Thanks!


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## Hallyx

shannonpwns said:


> If I have a sponge filter in my planted sorority, do I still need a HOB filter too?


Probably not. But I'd bet you'd have clearer water with the HOB running. You don't need it for bacteria purposes.


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## shannonpwns

Hallyx said:


> Probably not. But I'd bet you'd have clearer water with the HOB running. You don't need it for bacteria purposes.


Someone said I needed the hob for the plants. But I really don't want to get another filter...not cause of the cost, just because I prefer the sponge and I think there's good water movement. Especially if I remove the tube coming out the top.

I guess I just want some affirmation that I'm not killing my plants by being stubborn lol.


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## Hallyx

Plants don't really care about filters. As long as your lights are the right color temperature (Kelvin) with the right wattage and photoperiod, they'll flourish. Ferts are also important but, imo, less so.


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## avraptorhal

+1


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## Quinn

So I got the smallest kits of the hydro sponge filters and the lifts are too tall for my tanks! (6.5 long and a 10 gal), I have to have them tilted for the tubes to be under water at all. Is there anything besides new filters I can do, like trimming the tubes (not sure how even)? It doesn't make sense, these are what they are rated for, I understand the smaller tank a bit because it's a strange shape, but the regular 10 gal?


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## Hallyx

The smallest Hydro (the "mini") fits in a standard 5g with a half-inch to spare. You may have a larger version; the mini's foam sits 1/4 in, above the bottom.

The riser tube is cheap acrylic. You can cut it with a hot knife blade orsoldering iron (ventilate). You can hack-saw it by wrapping the tube in a layer of masking tape over the place to be cut. Mark the cut. Saw it round and round til it cuts through. Clean up the cut (carefully) with a sharp knife. Plug that end into the filter. Cut it off at least an inch below the surface. The longer the tube, the stronger the flow.

The Hyro allows the use of an airstone. This provides more flow and less surface disturbance. The directions are somewhere on this thread, or you can ask again.


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## Tikibirds

i still say this needs to be stickied


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