Last update: October 24, 2023

Aquarium Sponge Filters: Cheap Mechanical and Bio Filtration

Sponge filters are the cheapest and easiest way to filter your tank.

But don’t write these off as cheap and nasty because they are actually very effective!

In fact, your local fish store likely uses sponge filters in their tanks.

These guys are trusting sponge filters to take care of hundreds of thousands of dollar’s worth of fish…

Got your attention now?

I thought so.

Today, I am going to teach you everything you need to know about sponge filters.

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Poret foam sponge in different layers of PPI for sponge filter

Swiss Tropicals Poret Foam

  • Life of 5-10 years
  • Contains no unwanted chemical
  • Different shapes and sizes
Hikari sponge filter best for small and large aquariums

Hikari Bacto-Surge sponge filter

  • High quality
  • Provides outstanding mechanical and biological filtration
  • Unique air dispersion design
ATI Hydro Pro Sponge Filters In Different Sizes

Hydro sponge filter

  • Quality materials
  • Modular design
  • Affordable

What is a sponge filter, and how does it work?

Sponge filter for small 10-gallon tank

A sponge filter is little more than a piece of foam that sits inside your aquarium and filters your water.

No, seriously – it’s as simple as that!

While sponge filter designs vary from brand to brand, they are typically made up of four different parts:

Different parts of a sponge filter diagram

1. Foam sponge – It wouldn’t be a sponge filter without it.

2. Weighted base – Stops the sponge filter from floating around your tank. The sponge sits on top of this base.

3. Strainer and bulls eye – Slides inside the sponge and allows you to connect airline tubing directly to the filter.

4. Lift tube – Water flows up this and back into your tank.

While it may not look like much, these four parts actually form a very effective filter.

As for how a sponge filter works, well, it’s very clever…

How a sponge filter works diagram

With a good air pump attached, bubbles rise up the lift tube and out into your tank.

This forces water to be drawn through the foam sponge.

As water passes through the sponge, it catches and traps debris, such as fish poop, uneaten food and decaying plants, filtering it from the water.

Filtered water then passes through the lift tube and back into your tank.

While this filtration method may seem basic, it’s quite effective!

Since sponge filters don’t have a way to force water through them, they are used in conjunction with an air pump, airstone or powerhead. Without one, they are useless.

If you have never heard of a sponge filter before, it may surprise you to learn that they have been around a long time.

When my grandfather was growing up, his tank had a sponge filter – and it wasn’t exactly a new discovery then, or so he claims!

While they used to be the preferred way to filter an aquarium, advancements in filter technology have seen the sponge filter become less popular.

Sponges useful for your tank

While sponges continue to make a great cheap primary filter, they are also often used to add an extra layer of protection to your tank.

When used this way, sponge filters are sometimes referred to as pre-filter sponges because they are exactly that – a sponge that sits on your filter tube intake.

Water passes through the sponge before it reaches your filtration system.

Yep, you can use a sponge filter in addition to your primary filter, such as a canister filter, to preventing it from clogging.

Depending on your setup, a sponge filter could be the perfect addition to your aquarium.

Why do you need a sponge filter?

1. Easiest method of biological filtration

Your mother probably told you never to leave the sponge in the sink because it will grow bacteria.

She was right.

While this may be a bad thing in your kitchen, it’s fantastic in an aquarium.

As you probably know, natural bacteria in your aquarium break down waste and keep your fish happy and healthy.

Well, a sponge filter is the perfect breeding ground for these bacteria. Before long, you will have an entire colony happily calling your sponge filter home.

And because water is being sucked through the sponge, the bacteria will “clean” the water as it passes through. This is known as biological filtration and helps to keep your tank in balance.

2. It’s a 2-in-1filter: mechanical and biological

In addition to being a great bio filter, sponge filters are also more than capable of providing your tank with mechanical filtration.

The sponge traps bits of debris and filters them from your tank.

If you are unsatisfied with the mechanical filtration offered by your sponge filter, you likely need a stronger air pump to improve the water flow.

3. It’s fry and shrimp safe

Worried that your hang on back or canister filter is going to suck up the little critters in your tank?

Not a problem with a sponge filter!

A sponge filter placed on the filter tube can help prevent your tiny tank critters from being sucked up.

In addition to this, the bacteria that grow in the sponge filter are the same bacteria that fry and shrimp love to feed off.

4. It’s a filter that is always cycled!

Need to set up a new tank in a hurry, say to hospitalize a sick fish or for breeding? The sponge filter can be removed from your main tank and placed inside the new one.

You can even cycle multiple sponge filters at once by stacking them on top of each other and using a longer filter intake/stand pipe.

This way you will always have spare, cycled sponge filters on hand when you need them.

5. No strong current

Got a betta or other slow-moving fish that doesn’t like strong water currents?

A sponge filter provides gentle filtration, just make sure you don’t turn the air pump on too high or the rising bubbles will agitate the surface and stress your fish.

You can even add a pre-filter sponge to slow down the water flow on your existing setup to reduce water movement.

6. Power outage friendly

Let’s say you have a canister filter that stops working due to a power outage.

When the pump stops, so does the water flow to the canister. No water flow means no oxygen for the bacteria in your tank.

Because of the small capacity of a canister filter, the bacteria will soon “suffocate” and die.

But a sponge filter sits inside your tank with a much larger water volume, allowing the bacteria to survive for much longer than they would have inside your filter.

7. Sponge filters are cheap!

Let’s face it – fishkeeping can be an expensive hobby.

But a sponge filter is perhaps one of the most affordable pieces of aquarium equipment that you will come across. Well, except for maybe a fish net.

Whether you buy a pre-made sponge filter from a store or go the DIY route and make your own, you can pick up a sponge filter for just a few dollars.

Even more expensive brands can be purchased for less than $20.

What are the disadvantages of sponge filters?

But not everything about sponge filters is great.

1. Sponge filters are big and ugly

A sponge filter sits in your aquarium and looks like, well, a sponge.

Sponge filters can be quite large and, despite their dark color, will be clearly visible in your aquarium.

It certainly doesn’t look natural, and those trying to keep aquarium equipment out of the tank will be put off by the idea of a sponge filter.

2. No chemical filtration

Chemical filtration is a heated topic. Some aquarists swear by it while others dismiss it completely.[1]

While the debate continues, if chemical filtration is important to you, then you need an additional filter, likely activated carbon, to achieve this.

3. Hungry fish will try and eat it

Let’s say your sponge filter sucks in food…</>

To a hungry turtle or pleco, that sponge can look like a tasty meal.

As you can imagine, synthetic foam isn’t considered a part of a balanced diet for any living creature.

However, this can all be avoided if you keep your tank well fed on a regular basis.

A good automatic fish food feeder can really help while you are away from home for an extended period of time.

What are the best sponge filters?

The ideal sponge filter for your tank entirely depends on whether you are buying one from the store or going the homemade route.

Best store bought sponge filter

If you are going with store bought, there are two brands I recommend above all others – ATI (Hydro) and Hikari.

Both of these brands are commonly available, extremely well made and, best of all, affordable.

Just note that they do come in different sizes, from tiny sponge filters for nano tanks to large ones, so be sure to choose an appropriate size for your aquarium.

1. Hikari Bacto-Surge sponge filter

Hikari sponge filter best for small and large aquariums

SizeDimensionsAquarium size
Mini3-1/4″ x 2-1/2″ x 2-5/8″Up to 10 gallons
Small5″ x 5″ x 4.13″Up to 40 gallons
Large5″ x 5″ x 6″Up to 75 gallons
Extra large6.5″ x 6.5″ x 8″Up to 125 gallons

2. Hydro sponge filter

ATI Hydro Pro sponge filters in different sizes

ModelDimensionsAquarium size
Hydro II4″ x 2-3/4″Up to 20 gallons
Hydro III4″ x 3-3/4″Up to 40 gallons
Hydro IV4″ x 4-3/4″Up to 80 gallons
Hydro V4″ x 5-3/4″Up to 125 gallons

Best DIY Sponge Filter Foam – Swiss Tropicals Poret Foam

Poret foam sponge in different layers of PPI for sponge filter

If you build your own sponge filter, you want the best.

And, it doesn’t get any better than Swiss Tropical’s Poret Foam.

Not only does it have a long life of 5-10 years, but it contains no flame retardants, mold inhibitors or plasticizers – chemicals you really don’t want to add to your fish tank.

Foam blocks and sheets are available in a variety of different shapes and sizes and PPI.

What’s PPI?

Sponge filter foam is rated on a scale of pores per inch (PPI), the number of holes in the foam per inch.

The lower the PPI, the larger the holes. Ten PPI has 10 large holes in a square inch while 60 PPI has 60 smaller holes in the same area.

For an aquarium, 10 – 30 PPI is considered ideal. While the lower end won’t catch as much debris, it will clog slower. On the higher end, the sponge is great for filtering out tinier particles and polishing your water, but if it traps too many large debris, it could kill your bacteria.

Anything higher than 30 PPI and you will find that the small holes will clog too quickly, requiring constant cleaning.

How do you clean a sponge filter?

Over time, your sponge filter will begin to clog.

And when this happens, a quick clean is all it will take to get the sponge filter running as good as new.

The one thing you need to remember is:

Never clean a sponge filter with tap water!

A sponge filter contains bacteria essential to the health of your tank.

The chlorine in your tap water will kill all this bacteria, leaving you with a useless sponge.

While cleaning a sponge filter is easy enough, there are a few things you need to be mindful of.

For instance, if you reach into your tank to grab the sponge filter, you are going to leave behind all the gunk it has collected and make a real mess of your aquarium.

More mess to clean up. You don’t want that, do you?

I personally clean my sponge filter during a water change.

And here is exactly how I do it:

Step 1: Grab a fish bag

You know those bags you brought your fish home in?

Well, those make amazing filter cleaners.

I use 10” x 20” bags and always like to keep a few near my tank because they come in handy!

2. Scoop up your sponge filter

Now, you want to take your fish bag and dunk it in your aquarium and get some water in the bag.

Next, carefully scoop up your sponge filter from the bottom. With the bag opening above the water, disconnect the filter tube or pump line.

You will now have both your sponge filter and a generous amount of aquarium water inside the bag.

3. Squeeeeze the gunk out

It’s time for the messy part. Shove your hand inside the bag and give the sponge a good squeezing, working at the surface with your fingers and thumb.

The water inside the bag will soon turn brown as the sponge releases all the gunk and grime into the bag.

Empty the water out into your sink and scoop in some more clean aquarium water.

4. Repeat

Keep doing this until the water in the bag is relatively clear. It generally takes me 3-4 passes before I am satisfied that the sponge filter is “almost clean,” and the water is mostly clear.

By cleaning your sponge filter in your aquarium water, rather than water with chlorine, your beneficial bacteria will return to your tank alive and ready to remove ammonia and nitrites.

It doesn’t matter if your sponge filter still looks grimy, you are never going to get the sponge filter as clean as the day you bought it.

Remember: The sponge filter only has to be functional, meaning it doesn’t have to look like a work of art.

5. Return the sponge filter to your aquarium

Give the sponge filter one last squeeze to remove all the water before returning it from your tank.

You may notice tiny pieces of gunk float off your sponge filter when you return it to your tank.

This is normal, and as long as you followed the steps above, it shouldn’t be much at all. The sponge filter will suck these back up once it’s operating again.</p >

I find that I have a full month before my sponge filter needs to be cleaned again.

Navigating the World of Sponge Filter Sizes 

The task of choosing the right sponge filter can be daunting. I’ve realized that sponge filter sizes are super important. Too small, and it won’t handle the fish load; too large, and it might overpower your setup. From tiny to big sponge filters for aquariums, there’s a lot to consider.

If you’re setting up a 10-gallon tank, your best bet would be a small to medium-sized sponge filter. However, for bigger setups, say, a 20-gallon tank, you’ll want to go for a big sponge filter for aquariums. Got an even larger setup? If you’re working with 40 gallons or more, especially with a lot of fish, you’re going to need an extra-large filter. Trust me, you’ll thank yourself later.

Finding the Best Aquarium Sponge Filter for a 10-Gallon Tank

When I had to pick a sponge filter for my 10-gallon tank, several factors came into play:

  • Tank Size: I first gauged the actual volume of my tank. For a 10-gallon setup, a small to medium-sized sponge filter typically does the job.
  • Fish Load: I counted the number of fish and their sizes. For those of you dealing with a larger community of fish, a big sponge filter for aquariums might be a better fit.
  • Filter Efficiency: It’s not just about the size. The best aquarium sponge filter will balance mechanical and biological filtration well, ensuring not only clearer water but also a healthier environment for the fish.

So, with these considerations in mind, it became easier to pick the ideal sponge filter for my 10-gallon tank. And let me tell you, ever since I made the switch, my fish seem happier and my water has never looked better.

So, Does a Sponge Filter Clean Fish Poop? You Bet!

You might be asking yourself, “Does a sponge filter clean fish poop?” I had the same question when I first set up my aquarium. I quickly discovered that sponge filters are excellent for tackling fish waste, from the small particles to the murky stuff. They have a two-way action that’s impressed me: first, by trapping these solid particles in their porous structure, my water’s clarity improved; and second, by encouraging the growth of beneficial bacteria, which help break down fish waste into less harmful compounds.


As you see, there are several amazing reasons why a sponge filter would make a great addition to your tank.

Do you use a sponge filter? Let me know in the comments below!

Ian Sterling

Ian Sterling, founder of, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website,, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.

Comments (41)

Just finished adding sponge filtration to my 4 betta nano aquaria & my 29 gallon. For my 29 gallon purchase two ATI Hydro IIIs. For the smaller aquaria purchased an inexpensive (off shore brand) double head sponge filters.

How do you calculate the size of the pump needed for a sponge filter? I understand you can use an air pump or powehead but I can’t find anything on size. I have 5, 10, 30, &55 gal tanks.

Hi Jacoba,

Excellent question. Because a sponge filter is powered by an air pump, you simply buy an air pump that is rated to the size of your aquarium. Air pumps are rated in gallons, so simply match the air pump up with the size of your aquarium

I’ve seen and heard some people remove the lift tube because they don’t like to clean the algae from it. They say it still works fine without it. However, I tend to think there must be a reason the original inventor included the lift tube for a reason. I wonder if that reason is because it makes it more effective. Do you know?

Hi Craig,

That is an excellent question!

I have not seen anyone remove the lift tube of a sponge filter. Are these people using a powerhead to drive their sponge filter? If so, a lift tube may not be needed

However, if they are using an air pump to drive bubbles through an air stone, I am doubtful it is effective, even if it looks to work fine.

Firstly, the lift tube helps direct bubbles to the surface of your tank. This gives the sponge filter an “inflow” at the sponge and an “outflow” at the surface, which would help to keep flow of water movement consistent around the tank. Removing this tube would create irregular water movement as the bubbles would fan out once exiting the sponge.

Next, tube increases the amount of vacuum that can be generated, as the bubbles work their way up the lift tube, water is drawn in. If you remove the tube, I would expect their would be less flow through the sponge itself.

Finally, we live in an age where if manufacturers can cut the cost of a product, they will. If the lift tube was actually useless, manufacturers would have gotten rid of it long ago.

I use a small twin sponge air-driven unit in my 20 long hi-tech planted tank to supplement the canister filter which uses a larger twin sponge setup on the intake.
The large sponges on the canister intake must be cleaned once a week on an alternating schedule.
I draw out about a gallon of tank water, clean one of the sponges out in it and then inoculate a thoroughly cleaned and dried replacement by squeezing it repeatedly in the dirty water.
The smaller air-driven sponges do not require cleaning as often as the larger ones due to the lower flow rate produced by the air pump.
As a result, the bacteria in the smaller sponges remains fairly stable and there is always a sponge in the tank that has not been cleaned in over a month.

[EDIT: It has been over 6 months and Steve still has not provided a link to the patent he refers to. In my opinion, you should take his comments with a grain of salt]

Hi Steve,

I am a little confused here. I agree there are varying grades of sponge but can you clarify one thing… You have linked a source to backup your statement yet no mention of the Hikari Bacto-surge is made in the reference.

How did you arrive at your conclusion? Is this your article?

Don’t get me wrong, I love americanaquariumproducts as a resource, and often recommend it as a source of further information, where relevant. However, the author has been quite vague as to which brands he tested against the Hydro Sponge.

The writer of that article makes it VERY clear that all other sponge filters infringe upon a patent, constantly mentioning that the material and sponge filter is patented. In fact, there are 35 mentions of the product being patented across the article. It seems excessive, right? No other article I have read on that site goes out of it’s way to defend a product to such an extent.

To me, whether real or imagined, the article you have linked to reads with a strong bias towards the Hydro Sponge. Especially when every other brand of sponge filter is often referred to collectively as a “knock-off” or “cheap knock-off” instead of judging each brand on it’s merits.

Based on the different sponge filters I have on hand, they don’t all use the same sponge material. Considering the site responsible for these claims also sells the hydro sponge and no other brands, for me, it’s impossible to read this as an objective resource.

I mean no disrespect – I encourage debate on fishkeeping. It’s how the hobby progresses! But unlike other amazing americanaquariumproducts articles which are generally exceptional, from outwards impressions, this one feels like it has an agenda.

Ian, this is not my article, however I do in fact know the author the respect he has in the industry and community.
Your comment that it is not reliable information is really nothing than an Ad Hominem argument.
If you read his bio, you would know that he arrived at what he sells via decades of experience & research. So why should he not sell what he recommends? This goes for all his articles.

As for the Hikari, I did a quick re-read and he does mention this sponge filter.
Moreover I know that this is well known in the industry as a Chinese knock off that infringes on the patent, so supporting this over and American made one really makes me respectfully question your intentions too, especially when you link to Amazon which again is well known within the industry for the harm they are doing to the industry.

An article that addresses what Amazon is doing to our industry (there are more, including one I co-wrote):

As you said, I mean no disrespect, but I simply pointed out a fact, & you used it as a way to attack someone who has given much to this hobby and industry, often in ways many except those close to him could know

Hi Steve,

I was going to elaborate on my thoughts, but then something you said struck me as being off…

You said that he mentions the Hikari sponge filter in his article. I knew this to be false.

So imagine my confusion when I went back to his article and discovered that it does.

Fortunately for you, I love paper trails:

Check the date on my comment you are referring to:

December 11 2018.

Now check out this version of his webpage I saved on the exact same day I made my comment:

I was right. On 12/11/18 The Hikari filter isn’t mentioned in the article. Not once.

The author of this piece has added a mention of Hikari to his article AFTER my comment.

In fact, if we check his “current” article, it says it’s been updated on 4/14/19.

Now check out the date you left your comment. You had a full four months to reply to my original comment but decided to wait until now, the day after this update.

From outwards appearances, this “amendment” occurred at the same time you come here and leave a comment to discredit my opinion.

Given your relationship with the author, this all seems too coincidental to be unplanned.

I mean no disrespect, but all you have done is proven I was right to question his intentions. If my suspicions are true – Someone who would go to the lengths of editing an article to “prove a differing opinion wrong” is not someone who can be trusted. And now I have to question your role in all this too.

First of all, unlike the author who is online daily, I am only online a few times a month and do not check everything I respond too, especially blogs. I have indeed spoken with the author many times and know that he updates many times per year.
Your copy of an older version does indeed have the XY-380 which is one of MANY generic Chinese rip offs of the AAP/ATI Sponge Filter that most professionals in the industry are well familiar with. His adding is likely due to an attempt to make his article more clear with all the many names being put on the same rip off filters.
If you had taken the time to speak with a professional, you would know this as the XY-380 sponge filter was the first version coming out over a decade ago and now having others place their name on it.
As well you avoided the point that you are promoting Chinese made goods that are infringing on USA patents over USA made goods.
This is exactly what is destroying the industry along with Amazon, yet you continue to attack others who simply point out facts well known in our industry while linking to Amazon

Hi Steve,

You want your point addressed, sure.

Can you link me to these USA patents that are constantly referenced? In my search, I could not find them. I want to get the whole story before I comment. I assume since you and the author regularly cite these patents that they are readily available?

As for updating “many” times a year, he updated it twice last year, again only to add a few extra brands and very minor adjustments. Thats 2/365 days. You can see how you “magically” being online and commenting the same day as an author you speak with updates his article is dubious, right? Especially after not commenting for months. I’m not saying it’s coordinated, but if you were in my shoes, wouldn’t you find that dubious enough to doubt credibility?

Since I subscribe to AAPs FB page (& admittedly speak with him regularly), I know this has been edited many more than 2 times last year.
Most of his followers both in forums and social media as well as the 1000s of hits his articles get per week know this well too.
But that is beside the point, as he already had XY-380 which is the original Chinese made product utilizing the patent, just like SunSun makes products under many labels in China (again if allowed for some mentoring from some professionals in the industry, you would know this). What is interesting, is I know that Carl in many of his updates in all his articles has made changes based on comments which includes corrections, yet you take my minor comment to attack others. I know that some of the feedback has not always been polite either, but even then, if it exposes an error, it is still updated. Adding names of products now re-branding the XY sponge filters is likely nothing more than this.

As for the patent, this too is well known and quickly found. But even here, why would you promote a Chinese made product over a better USA made product?

All I came in here to state was that the Hikari would not be as good a choice based on the points I’ve made. You made many good points in this article otherwise, but instead you took my comment to attack me and a professional who has spent his life in this industry, all the while promoting Amazon.
I’ve already shared this with others in the industry.

Anyway, I wish you good luck with your endeavors.

Hi Steve,

Not only did you fail to address my concerns in my last comment, you confirmed your bias (either deliberately or unintentionally) so I’m just going to break it down quoting you:

I know this has been edited many more than 2 times last year. Most of his followers both in forums and social media as well as the 1000s of hits his articles get per week know this well too.

Oh, you know it, do you? This perfectly illustrates why I don’t trust you, you confidently insist on things that are provably wrong – even going so far to add that “followers and 1000s of hits” think the same, as if that adds credibility to your untruth.

You are wrong.

You can check Carl’s edit history on his article here:*/

This service is run by the wikimedia organization as a way to archive the web.

As you can see, the article was only edited 3 times in 2018. Is that “many more times than two?” Rather than fact check, it appears you made up a false statement instead.

As for the patent, this too is well known and quickly found.

Speaking of facts, I wanted to check out the sponge filter patent so I can see if these products do infringe. I couldn’t find it.

When I ask you for it, you say it can be easily found and then you chose to link back to an article that BOTH you AND Carl created instead of the actual patent documentation, which isn’t found on your page. I couldn’t think of a more biased resource for you to link to in the scope of this discussion.

Anyway, YOUR article claims that “Aquarium Technology Inc” patented the original sponge filter. I couldn’t find a patent by that company using a quick patent search. If it’s so easy to find then why are you not sharing it?

But even here, why would you promote a Chinese made product over a better USA made product?

I’m all for American made products, but you are shifting the goalposts of this discussion:

Your entire argument is based on these sponge filters infringing on a patent. That was what started this discussion, right?

If these don’t infringe on a patent, then it brings me full circle to my original comment – that article has an agenda. Which, I might add, I currently stand behind as you have failed to provide proof otherwise.

I must stress here, that I am open to changing my mind, but every reply you give reeks of bias. I want to trust you, I really do, as I can see you have some great resources, but from this back and forth, you insist on voluntarily tearing your own credibility to shreds.

I’ve already shared this with others in the industry.

Thanks for the shout out! Always happy to have new readers.

I’m not even going to go into the personal jab about mentoring. That’s pitiful.

Eagerly awaiting your response with a link to that easily found patent!

Hi Ian,
I appreciate your blog in general! I purchased a sponge filter for my 5 gallon tank that houses 1 Betta (the mini Hikari, and the Tetra Whisper Air Pump for up to 10 gallons) to provide gentler circulation compared to the last filter I had. However, the bubbles are agitating the surface so much. I have a bleed valve on it to let air escape the line and get it to the slowest stream of bubbles I can without having no air running through the sponge. At this level, though, the bubbles eventually stop (seems like every 30 minutes, give or take). I don’t want the whole filtration process to stop randomly, so is there a way to balance decent air flow with keeping my Betta stress-free?

As a side note, I am currently running the old filter and the sponge filter at the same time to get the beneficial bacteria to establish in the new sponge.

Thanks in advance,

Hi Brody,

I’m a little puzzled by the fact that your air stream is eventually stopping. Is this because of a faulty fitting on your bleed valve or because of the pump itself. Because if a constant rate of air is passing though, the bubbles shouldn’t stop.

Worst case scenario, Try using the control valve on the actual line going to the sponge and you’ll have to deal with the back-pressure.

Thanks for your response. I changed out the bleed valve and the bubbles have been constant ever since. I never would have thought of that, so I appreciate your help!

for 10 gallon aquarium.. i think you can choose either small sponge filter or air stone only.. your requirement for 10 gallon tank is 2-lpm to 3-lpm air pump.. dont buy an air pump that have power more thank 3 lpm.. that my opinion

Hi Syrl,

Thanks for the kind words. Your anaylysis is spot on, a sponge filter should work just fine for an axolotl!

I use the sponge filters and love them but I found out I’m cleaning them wrong. I’m using my water from the tap, instead of the old fish water.
How long does these filters last???

Hi Naomi,

Depending on the brand, these filters can last years, regular tank maintenance will ensure they don’t clog too quickly. It’s important that you use tank water as chlorine will kill any beneficial bacteria inside.


Just want to know, if the mini sponge filter can keep plant alive. I just have one Anubias plant tied up in a rock…substrate is construction soil. Dimensions 12length, 12 height&10width.

Hi Abhisekh,

Plants don’t necessarily need filters but they do need some degree of water movement, and a sponge filter + airstone helps with that.

Hey, I am planning to put 7 fancy goldfish in a 100 gallon tank so, will a single Hydro V sponge filter work or do I need multiple of them? Waiting for your answer. Thanks in advance

Thanks for this article it’s a very interesting read, I have 2 sponge filters running along with 2 canisters in my 180, when I do water changes I add tap water straight back into the tank adding SP to cover the full tank. I turn off my canister filters so no chlorine goes through them during filling should I be removing the sponge filters every time I do a water change as well or will the BB survive leaving them in? Thanks for your help

Hi Andy,

This is an interesting question. I would assume that if you are adding SP quickly, the bacteria should be fine. I say this anecdotally as I have seen numerous fishkeepers who only use sponge filters use water changes without crashing their cycle, again adding dechlorinator as it enters the tank.

I’m hoping your right, as I’m sure my LFS wouldn’t take out the SF every time they do a change. Thanks for your speedy response much appreciated.


Hi Andy,

It sounds like you have a good lead there. I would ask your local fish store how they do it. You might even find they have a trick or two to teach you to make the whole water change process easier!

I currently use a DIY siphon much like the python system which is very effective though I’m always happy to make improvements.

Thanks again

Hi Ian, if I have a 30 gallon tank will having a sponge filter for its size and then another smaller sponger filter be healthier, or would that be some sort of “over filtering” (beginner question)

Hi Joey,

There isn’t really such a thing as “too much” biofiltration, since the beneficial bacteria colony adjusts itself to the waste produced in your aquarium. It’s always better to have more filtration than not enough.

The advantage of having two sponge filters is that if you (or you know some one else) ever want to start a new tank, you have a cycled filter there ready to go – you can use this to basically skip the new cycling process that new tanks go through.

The only concern with two sponge filters would be that they rely on an air pump to run. Each additional sponge filter will require more air, which increases the water movement around your tank. For many fish, this isn’t an issue. But certain fish prefer distinctly calmer water, such as betta – even moderate water movement can stress them out. Of course, this all depends on which fish you add to your tank. If you are adding a “still water” preferring fish, you can always adjust the airflow to reduce current.

Question : I am making a plant and betta tank using a “20 Long” tank. My thought was to put two sponge filters (one on each end). Do you think this is too much and/or bad idea (and why)? And if it will work, should I get two of the filters that go up to 20 gallons (since it is 20 gallon tank) OR two of the 10 gallon filters (since I want two)?

Appreciate any advice.

Hi Tigris,

This is an excellent idea. You can never have too much filtration. If it was me, I would buy 2 x 20 gallon ones. This way, if you ever wanted to set up a new tank (or know someone else who does), you will have a fully cycled sponge filter ready to go, so you can skip the cycling process.

Just make sure that you turn the air flow down if it’s making too much current. Betta prefer clam water and too much water movement can stress them out.

I am new to fish keeping and haven’t even set up my tank in fear of doing it wrong. I see that you’re right about the looks of the sponge. Is there no way to have a natural looking sponge filter? I would assume given the fact that it is just a sponge that can be shaped/molded that there would be one out there. No?

Hi Dana,

Interesting question. You don’t want to compress the sponge since that will restrict water flow which defeats the purpose of the filter. However, you can hide these behind plants or decorations if you so choose.

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