# Sponge Filters



## jeff12 (Oct 21, 2011)

I always have used HOB for filtration and never sponge filters because I don't really know how they work. For my new 55 gallon I plan on getting into sponge filters because they're cheap. How do they work? Are they loud? Do you have to replace them? Any good ones from experience? Also, for air pumps is the bigger or the larger gallon capacity mean that it's stronger and pumps faster? What do you u guys use for ur air pumps?


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## BillD (May 17, 2005)

Sponge filters are a very inexpensive way of providing biological filtration. As well they collect a surprising amount of material from the water, hence the need for cleaning. I have been using ATI Hydrosponge filters and like them. The only knock against them is that the two pieces that make up the internal sleeve break easily. They spilt where they join. You can usually glue the cracks back together with crazy glue. It is a good design and they work well. As to air pumps, a gallon rating doesn't really tell you a lot, as a bigger tank doesn't necessarily need more air than a small one with regards to powering the filter. You can also run them with a powerhead which makes them very quiet. Typically, those with a lot of tanks will run sponge filters powered by one pump, with the air distributed around the room using a manifold.
Air powered filters work by creating an area of lower density on the lift tube. The mix of air bubbles and water is less dense than the surrounding water, so, gravity acting on the water forces the water into the less dense area. The less dense area is inside the tube so the water moves through the sponge to get to the tube. My experience has been that fine bubbles work better than big ones. The longer the total length of the tube, the greater the "lift".


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## jeff12 (Oct 21, 2011)

Does the flow rate of the air pump affect the sponge filter? Will it create bigger bubbles and be noisier? Is a higher flow rate equal to a faster turnover rate of the tank?


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## BillD (May 17, 2005)

More air means more flow, to a point. You could actually have too much air and no flow. Bigger bubbles tend to be noisier, but they also move faster which I believe slows the flow. If you use sponge filters you need to forget all the nonsense about turnover and flow. Bottom line is "do they work?"; the simple answer is yes, and at very low "turnover" rates.


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## smitty (May 7, 2004)

If you want a filter with a sponge I would just get a Aqua-Clear


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## jeff12 (Oct 21, 2011)

I actually already have a few aquaclears but I need more filters so I am going with sponge filters because they're cheaper.

Are their any factors that affect the noise, bubbles, and the flow, such as the size of the tubbing?


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## BillD (May 17, 2005)

Smaller bubbles work better in my experience and are much quieter than large bubbles from an open air line. The length and diameter of the lift tube will determine how much water will move, assuming you have enough air. The taller lift tube will provide a larger pressure differential between the bottom, where the water enters, and the top, where the water exits.


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## RobsFishTank (Nov 11, 2014)

I use sponge filters with power heads as secondary filtration. A canister or HOB filter does most of the work of removing debris and the sponge, which hardly ever needs cleaning, gives a polishing effect to the water. The advantage of using a power head is you can direct the flow towards an area that doesn't get much circulation.


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## DrgRcr (Jun 23, 2009)

I have sponge filters in all but one of my 24 tanks that run off a single diaphragm air pump. In a few fry and grow out tanks, they are the ONLY filtration. They provide a large amount of area for bio filtration and are cheap. In the even of a power outage, I would need very little power to run the air pump and hence still have some type of filtration running in the tanks. Compare that to the power consumption to run at least an HOB or canister on every tank and you can see the big advantage.

FWIW, the Hydro Pros with the coarser sponges work better than the standard Hydros. For finer bubbles, I like to use a short piece of airline with an air stone attached to the bulls eye inside the sponge.


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## jeff12 (Oct 21, 2011)

Is a control valve and check valve needed for a sponge filter? I was watching a tutorial and they added that to the sponge filter. They also added a air stone too. Does the airstone give a better flow and suction? What would give maximum suction and flow?

I have set up my sponge filter for my fry tank but it seems the water is a bit cloudy, it still clear but not the way the HOB was doing. I see videos of people with crystal clear water with only sponge filters.


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## Deeda (Oct 12, 2012)

If the air pump is located above the water level of your highest tank, there is no need for a check valve. The check valve is meant to avoid siphoning water out of the tank in the event of a power outage or air pump failure if the pump is located below water level.

An air valve or gang valve (multiple valves) is used to control the amount of air to each sponge filter.

An air stone provides smaller bubbles but do require regular replacement due to clogging and age. I don't use them for that reason.

What brand and model air pump and sponge filters are you using? How many sponge filters are you planning on operating?


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## RobsFishTank (Nov 11, 2014)

Most of my tanks have started with HOBs (and more recently canisters) with the sponge filters being added shortly afterwards. It's not on purpose, it just works out that way. The water is "clear" when I add them but there is always a polishing effect from the sponge filter making the water crystal clear. Having some sort of decent mechanical filtration takes the bulk of the work away from the sponge, letting it do the biological and finer filtration without getting clogged, actually extending the life of the sponge.


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## jeff12 (Oct 21, 2011)

Deeda said:


> If the air pump is located above the water level of your highest tank, there is no need for a check valve. The check valve is meant to avoid siphoning water out of the tank in the event of a power outage or air pump failure if the pump is located below water level.
> 
> An air valve or gang valve (multiple valves) is used to control the amount of air to each sponge filter.
> 
> ...


Which is more effective, in terms of filtration, bigger or smaller bubbles?

The air pump is located under the tank.

I am using the Whisper 20 for my 10 gallon with only one Hydro #3.


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## RobsFishTank (Nov 11, 2014)

jeff12 said:


> Which is more effective, in terms of filtration, bigger or smaller bubbles?


Smaller bubbles are usually more effective but there is a balance as to how much actual benefit you actually get at such a small scale as a 10 gal tank. "Big" bubbles should get you the flow you need through "standard" filters. I've worked in a few fish stores and they all had air driven filters that had big bubbles in the smaller tanks.


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