How Aquarium Sponge Filters Work—Working, Setup and Use

How Aquarium Sponge Filters Work—Working, Setup and Use

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It’s pretty easy for new fish keepers to underestimate the cleaning capacity of sponge filters, but with time, and like all hobbyists, most start to appreciate the ability of these units.

Sponge filters measure up in effectiveness to any other aquarium filter type (read more on filter types) in the market if used correctly, though some people struggle with it all the time.

How I know this is from the ton of questions I get!

Quite a number have told me, rather casually, that all they see is bubbles, and with that, they believe the filter is working and will clear their tank, and if not, kick it to the curb and get a different filter system.

Well, in this post, we are going to get into how sponge filters work and the best place to use them. If not for nothing more, to at least demystify their appropriateness and effectiveness in keeping your aquarium water clean.

What is A Sponge Filter for an Aquarium

To understand how it works, you have to know what it is, yes😃?

A sponge filter is precisely what the name implies, a sponge through which the aquarium water is drawn. This provides mechanical filtration, and once the media has matured and grown bacteria colonies, it provides biological filtration as well. the spruce pets

Sponge filters are somewhat small units compared to power and canisters filters, hence viewed only as an option for bowls and beginners.

But nothing could be further from the truth.

Sure, they are probably the best alternative for small tanks like 10-gallons that do not require a lot of water movement and surface agitation, but they can also be used in biggers fish tanks with larger-stock, either as the chief or secondary filtration unit.

Basically, sponge filter use a foam-like media to clear your water when it’s passed through the system. Mostly, the flow is initiated through an air pump, though a powerhead will work as well.

From experience, sponge filters can be used for biochemical filtration (box type), but they usually have superior biological cleaning capacity. Sometimes, the sponge will even trap solid debris much like a mechanical-filters albeit less effectively.

That said, please note that sponge filters come in varying sizes and configurations depending on the brand design, but the working process is pretty much standard.

For instance, you’ll get one that comes in a dual-sponge arrangement (wall hang sponge filters), and with two suctions at the back, which are used to attach it to the tank. Those with one attachment point tend to fall into the water quite often.

An advantage of the dual-sponge configuration, as opposed to sinking style sponge filters, is that you can take one sponge from the unit and use it to seed a new tank, while the second one remains in your main aquarium.

Another remarkable feature that is not always present is a directional output. What this does is help you change the direction of the current, which you can point to the said of the aquarium, especially when keeping slow-swimmers like betta that don’t enjoy too much water movement.

Also, kindly note that box filters are a different type of filter you will see quite often and that some people call sponge filter, but it is not; well not exactly.

Both filtration systems work on the same concept using air to create a suction vacuum and move water through a sponge media, but box filters are a lot more customizable.

In fact, when I said sponge filters can be used for biochemical filtration, I actually meant box filters because they provide a space for you to add a biological media (sponge) and chemical media.

How Sponge Filters Clean Aquarium Water

The working dynamics of a sponge filter are pretty straightforward; nothing too sophisticated. But obviously, it can be confusing because when you plug it in, you’ll only see bubble but not water getting sucked into the filter intake.

Essentially, water is pulled past a colonized filter media (sponge) via a single lift tube. Most standard units use an air pump to push the water from the tank to the filtration system, while large assemblies use powerheads instead.

When you purchase your sponge filter, it will have a small airline just next to the lift tube where you connect the air pump.

Through that opening, air will get blown into the body of the filter, go past the suction section and then rise via the lift-hose, which then creates the bubbles you see.

Once in the filter suction part, the air will draw water from the tank, through the sponge where it’s filtered, then together with the air-bubble, it will rise through the lift tube to leave the filter system clean.

As you may already have noticed, the part where the sponge media sit, which is the (or are) the inlets, will have slots that let water into the filter unit once the suction is created by the air pump or powerhead.

Of course, like any biological filtration system, your sponge will need to have a developed bacteria colony to clean your water.

How to Setup Your Sponge Filter

Now that you’ve got your sponge filter, you might be wondering how to put it together, which is easy, but it’s understandable if you cant set it up with no much experience.

Well, below is a quick step to step guide.

  1. The first thing you want to do is make sure you have everything you need. Counter check that you have the sponge filter, airline tubing, an air pump rated for your aquarium size, check valve, and airstone (if you are going to use one).
  2. You also want to counter check that your sponge filter has all the parts present. Ideally, you should be able to identify the foam sponge, lift tube, and the weighted bottom or suction attachment points for wall hang sponge filters. Inside the sponge, ensure you have a stainer and a top for it with a bullseye.
  3. To start the setup, attach your airline to the nipple on the top part of the life-tube. You will notice there is also a little plastic stalk that’s above the nipple, so make sure your tubing goes through it first, and remember to put it back in place once the airline is well in place.
  4. Now, there is a little variation between setting up a sponge filter with an airstone and putting it together independently. As such, the following two steps are crucial if you are going to add your unit with the airstone, which is recommended to create smaller bubbles and keep the filter quite.
  5. Some sponge filter have an extra nipple at the bottom of the top plate of the lift tube, that you can plug an airline into and put airstone towards the bottom.
  6. If your sponge filter does not have a second nipple, but you want to add an airstone, run the air tube through the small holes next to the nipple and run the airline all the way to the bottom.
  7. After that, the only other thing you would need to do before connecting your filter to the air source is to install the check valve. This is particularly crucial if your air pump is located anywhere below the surface of the tank to prevent backflow. Make sure you add your check valve the right way, with the air system on the side that the air goes through.
  8. A lot of people like to put the valve right up by the rim of the tank, that way it doesn’t have to push all the extra water over, but you can also put it somewhere along the back of the tank either closer or a little further away from the air pump.
  9. The last step would then be to plug your filter into the air pump, and it will come on and start cleaning your tank.
  10. Now, if you have a double sponge filter style, you might not have a lot of space for an airstone, but you’ll have a nipple somewhere along the center column or plastic tube that goes all the way to the top where you plug your airline.
  11. Please see this article for an explation with pictures.

Aquarium Sponge Filter Benefits

Sponge filters have several benefits that make them an exceptional buy, from being pretty affordable to creating almost no water movement best for fry and slow-swimmers like betta and angelfish.

See below all the benefits you will get from using sponge filters, and the best fish tank to use them, albeit a little later.

#1 — Affordable

Sponge filters are probably the cheapest aquarium filtration kits, and also quite accessible.

You are bound to get one from your local fish store, and even in bigger chain stores like Petco and PetSmart for a price anywhere from a 5 USD to 15USD.

Compared to canister filters, which can cost as much as 120 dollars for a basic Fluval 206, sponge filters are more accessible even in times of emergencies, for instance, when you need to set up a hospital tank.

That said, you will notice that some stores intentionally fail to stock sponge filters as much, or at least try to talk you into buying HOB and canisters units.

Why is that you ask?

Either of two things…

…one, they might have your best interest at heart and be honestly wanting you to get a filter that is appropriate for your tank size…

…or they are just putting their effort on the money because purchasing a different filter type means more accessories and revenue for their business.

So, take a minute, listen to the shop assistant advice, but also, if you only have a small tank with a low bio-load or you’re sure you don’t need a canisters filter, just go with a sponge unit and save your dollars.

Moreover, if you fancy getting your aquarium supplies online, you can purchase a sponge filter online from Amazon for about the same price you would buy one from your local pet store.

#2 — Simple

Of course, for the price you pay to get a sponge filter, it can only be a simple unit to operate. It does not have any complicated parts like a canister filter, and even setting one up is pretty straightforward.

Apart from a separate air pump, the filtration unit, and the filter media (sponge), the only other parts are the airlines you need to join the said parts.

As such, cleaning a sponge filter is also quite simple, with only the media needing regular cleaning, maybe once or twice a month or so.

#3 — Rather Quiet

Keeping your fish tank filter quiet can be a challenge since all units are designed to run on electric power. However, some are silent than others, and sponge units are right up there with canister systems.

They rarely make any cranking or humming sounds and don’t create the dreaded waterfall noise associated with HOBs either.

The most noise you can expect from a sponge filter unit is the humming of the air pump that powers the filtration cycle, and even that is rather minimal considering the pump size.

But please note that if the pump is resting on your stand, it might create a resonance with the wood, which can easily skew to the less desirable side of annoying.

So, try resting your pump on a piece of sponge or foam or put it on the floor if you have a carpet. Some people even place them in large containers so that it hangs suspended in mid-air, thereby eliminating contact between the pump-body and stand.

On some occasions, aquarists also complain about the sound of bubbles breaking the surface of the water. Personally, I find the noise tranquilizing, though not to say it can’t be annoying.

And while there is nothing much that can be done, having a fully enclosed hood will muffle the noise a bit.

The size of the bubbles will also make a difference, with bigger ones making a louder gurgling sound, and smaller bubbles creating a quieter fizzy noise.

From experience, the easiest way to create smaller bubbles is by passing an air stone attached to the airline inside the pump.

#3 — Partner Well with Other Filters

I’m sure you’ve had from forums and Facebook aquarium groups that sponge filter works well as a secondary filtration system to assist other units like canisters.

Which is true, though sponge filters can act as the principal filter as well.

These units partner well with other filters because they are small and don’t take up too much space in the tank, plus they are not overly powerful.

Their ease of use and maintenance also make them quite helpful, particularly when you need to clean your chief filter.

Intriguingly, sponge filters can even be used as pre-filters on the inlet of canister units to clean out a good deal of large particulate matter and keep the canister from clogging.

You will only need to clean your sponge filter more instead of the more tasking canister filter.

In terms of functionality, sponge filters have superior biological filtration capacity, as such, are usable in tanks with fish that has a high bio-load, which can be overwhelming for a single filter unit.

Another pro is the versatility of sponge filters, they can be used in literally any aquarium setup, anywhere from planted to hospital and quarantine tank. This makes them compatible with filtration systems of whichever kind.

#4 — Low Water Movement, High Surface Agitation

Using powerful filters like HOBs can result in a lot of water movement, which although preferred by some tropical fish species, slow swimmers like betta and angelfish struggle in such an environment.

You also do not want to use powerful units in a tank with baby fishes or species like kuhli loach that easily get sucked into the filter intake.

Instead, use sponge filters in such tanks to better protect your fish and fishlets

Conviniently, such fish like betta and fry can live even in small beginners aquariums, which coincides with the best size tank to use with a sponge filter.

Best Fish Tank Setup to Use A Sponge Filter

Mostly, the logic of using a sponge filter in a fish tank is the type dependability, in that they can fit in any tank setting including specific use setup like quarantine tanks.

The ease of use, affordability, and low water movement are all factors to consider. You also won’t have to deal with lost fish because they got sucked into the filtration system.

From experience, below are the best setup to use sponge filters, and in fact, some of these will best function with this type of filter without too much havoc.

  • Betta tank
  • Breeding tanks
  • Fry tank
  • Quarantine tank
  • New fish tank
  • Shrimp tank
  • Hospital tank
  • Small beginner fish tanks
  • Larger fish tanks as a secondary filter

That’s all for sponge filter, enjoy the hobby.

Eddie Waithaka

Resident Content Creator and Marketer at AquariaWise who talks about aquariums and fish and aquascapes a lot.

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