Image Credit: Tahir Mq (CC License)
Sponge filters are unsung heroes. These humble filters are super functional and helpful on many occasions but are often kept on the backburner to favor a HOB or canister filter.
Sure, HOB and canister filters have their advantages, but a sponge filter that looks so plain and ‘dull’ comes with a set of bells and whistles too.
So, for today’s edition, I’m going to share all there’s to know about sponge filters – the good, the bad, and the ugly. Are sponge filters any good?
Keep reading to know!
Are Sponge Filters Good?
Yes, sponge filters are good. Matter of fact, they’re very good at keeping the tank clean – they support mechanical and biological filtration. Sponge filters are especially useful if you have a small tank used as a hospital tank or a breeding tank. They come cheap and operate quietly,
Before we discuss the advantages of sponge filters, let’s look at what it actually is and how it works.
What Is A Sponge Filter?
A sponge filter is a super simple water filter with mechanical and biological filtration options. Appearance-wise, it looks like a simple piece of foam with a pipe sticking out of it.
People are often taken aback when they get to know about a sponge filter’s simple anatomy, but only a few know that the foam filter doubles up as a biological and mechanical filtration unit.
Based on the size of the pores, you can eliminate different kinds of waste as water passes through. At the same time, the extra surface area will allow beneficial bacteria to colonize.
So, the longer the sponge sits in place, the more advanced the biological filtration is. All of those nooks, crannies and little pores will add up to a thriving good bacteria colony.
And you know what that means – plenty of active filtration.
Sponge filters come in all kinds of different shapes, sizes, and even pore dimensions. But a well-made sponge filter should have the following components:
Better the foam sponge, better the quality of the sponge filter. As the name gives away, the sponge is the pivot around which mechanical and biological filtration work.
For example, the sponge will be the breeding ground for beneficial bacteria – strengthening the tank’s biological filtration system. An ideal sponge filter would have plenty of surface area.
A weighted base keeps the sponge filter from floating away or getting dragged around by the tank’s inhabitants. This base can be anchored against aquarium rocks or gravel.
These days, some sponge filters come with a suction cup mount in place of a weighted base. These are particularly helpful in bare bottom setups.
Bull’s Eye And Strainer
The bull’s eye enables you to connect your airline tubing directly to the sponge filter from the air pump, whereas the strainer keeps the food particles and detritus out of the sponge filter.
Low-price sponge filters often don’t have these components. Instead, they come with an airline hose connector that sticks out externally from the filter.
The lift tube helps move the water from the sponge filter to the rest of the tank. This tube can be used on high-end and larger models to connect the sponger filter to a powerhead.
Now, this results in a quieter and more efficient filter.
Some sponge filters may also have a lift tube that extends higher, so the bubbles created by the air pump are less disruptive.
Now that we are well acquainted with sponge filters and how they work, let’s quickly go through the benefits of installing a sponge filter.
Benefits Of A Sponge Filter
- It strengthens tank’s biological filter
- It comes cheap
- It is simple
- It produces gentle current
- It can be easily repaired or replaced
- It is super quiet
- It makes great pre-filter
It Strengthens Tank’s Biological Filter
We’ve already discussed how sponge filters provide additional surface area. So, the thing is that as the sponge matures, a colony of bacteria will make a home within the pores and along the entire surface of the synthetic material.
The good bacteria will work as a part of your tank’s biological filter. And you already know their role in keeping the ammonia and nitrate levels in check.
The best thing about a sponge filter is you don’t need to do anything once you install the filter. The biological process happens naturally. Good bacteria from the tank’s miniature ecosystem will climb their way to the filter and take the hassle in their stride.
It Comes Cheap
Sponge filters provide a bang for the buck. However, these filters have fallen out of favor in the fishkeeping hobby.
In the case of other filters, a trip to your LFS means buying charcoal media, frames, bags, an electric pump, and a zillion other accessories required to run the filter.
This way, you’d pay more than you would for a simple sponge filter with every visit.
Since a sponge filter’s setup includes a simple sponge and plastic housing, these filters are inexpensive and generate little income for the seller.
This is also why you will only find a few sponge filters on display at your LFS.
P.S. I don’t mean to shun other kinds of filters. Customizable media is superb for treating particular imbalances in the aquarium ecosystem.
However, if you have a healthy tank with moderate to low bioload, a sponge filter is an excellent choice when comparing the price to efficiency.
It Is Simple
Sponge filters are, well, simple. It’s just a sponge with plastic housing. The mechanism is straightforward.
The most commonly available design uses a strainer and a lift tube with an attachment at the top for a pump’s silicone airline.
When the bubbles are created within the strainer and lift tube and rise, the bubbles produce a soft current that pulls water through the sponge.
Initially, the filter only offers mechanical filtration. However, as beneficial bacteria colonize the filter over time, it will also provide biological filtration.
It Produces Gentle Current
A sponge filter is the ultimate option if you need to create an extremely gentle current in the tank.
For instance, if you’re raising fry, tiny organisms, and brine shrimp or incubating eggs, a powerful filtration will suck them up and effectively kill them.
So, by using a small air pump, the regulators on the filter, or the pump itself, you can offer ample biological and mechanical filtration without harming the inhabitants.
Although the turnover rate is relatively low compared to a canister or HOB style filter, it’s not necessarily less effective.
Spawners that breed throughout the year, like livebearers, often lose their entire batch of fry to powerful filter intakes. So, if you plan to raise juniors but never know when they will arrive, adding a sponge filter will be wise.
It Can Be Easily Repaired Or Replaced
Most filters these days are built with rigid components and are harder to repair or replace any part. For instance, gravel or rocks eventually get inside the components of an electric filter and cause problems.
Likewise, canister filters need you to detach the hoses and pipes, undo the locks, and occasionally bring out the manual for complicated issues or reassembling your components.
But sponge filters are as simple as they come. The worst that can happen is the sponges will decay, or plastic will crack. And guess what? Both these nuisances are easy to identify and replace.
If you’re someone as less tech-savvy as me, sponge filters will make the best choice!
It Is Super Quiet
The quietness of a sponge filter is determined by the pump that drives it. With rubberized seals and the advancement offered by today’s brand, these pumps can be quiet enough to not wake up a sleeping dog.
A sponge filter causes considerably less surface agitation than other filter styles that emulate the sound of a miniature waterfall. While this would make great background noise, sometimes silence is better – isn’t it?
And don’t worry about the filter’s compromised capacity for surface agitation. Sponge filters more than make up for it by providing ample gas exchange due to the constant flow of air bubbles.
Both oxygen and carbon dioxide will be exchanged in enough amounts for the fish and plants, respectively.
It Makes Great Pre-Filter
Even if you use a canister or a HOB filter, you can still incorporate the goodness and benefits of a sponge filter at a fraction of the cost. Instead of purchasing a separate unit, simply put a foam block over the intake.
This will impart most of the benefits of a separate sponge filter, enabling you to get the best of both chemical and biological filtration.
Adding a sponge block on top of the intake also helps protect small fish and shrimps from getting sucked in by the suction power of big canister filters.
Over a few weeks, beneficial bacteria will colonize the sponge in a similar fashion as they would colonize a sponge filter.
But bear in mind that since the surface area is relatively small, the main filter will do most of the biological filtration work.
I explained just 7 benefits to keep the article short. However, here is a glimpse at honorable mentions:
- It can be used in any aquarium type
- It works even during a power outage
- It is easy to clean
- It prevents prevent new tank syndrome
However, it’s not always rainbows and butterflies. Sponge filters come with a fair share of caveats too. Some of them are:
- They are big and not very attractive
- They don’t support chemical filtration
- Sometimes, fish attempt to eat the sponge
Now, let’s look at some of the most frequently asked questions on sponge filters on the internet.
Frequently Asked Questions
Are Sponge Filters Good For Turtles?
Unfortunately, no – sponge filters are not good enough for turtles. Turtles are super messy creatures and require a large tank. A sponge filter would not be able to handle the gunk created in a turtle tank daily.
You can opt for powerful canister or HOB filters instead. If you want to use a sponge filter, run it on a powerhead. Working it with an air pump won’t work nearly as well.
Are Sponge Filters Good For Bettas?
For bettas, beauty comes at a price. Their dramatic fins and tail prevent them from swimming efficiently. Therefore, they require soft currents that can be produced with a sponge filter.
If the current is too strong, like the ones produced by a canister or a HOB filter, the fish would have a tough time staying afloat.
Are Sponge Filters Good For Goldfish?
Goldfish are the turtles of the fish world. They produce a lot of waste daily. On top of that, they grow pretty big and need a massive tank.
So, no – sponge filters are not powerful enough for a goldfish tank. It’s best to bet your money on a canister or a HOB filter.
Do Sponge Filters Actually Work?
Yes, sponge filters work. They are equipped with mechanical and biological filtration systems that do an excellent job of keeping the water clean.
Are Sponge Filters Better Than Regular Filters?
A sponge filter is better than a regular filter (HOBs and Canisters) if you’re setting up a breeding tank, a hospital tank, a shrimp tank, or a small fish tank.
However, answering this question is kind of tricky. All filter types have their unique sets of pros and cons. So, the best filter differs from one tank to another.
Do Sponge Filters Keep The Water Clean?
As the sponge pulls water through its porous surface, it will trap debris – making the water clean as it is passed out of the filter at the top. So, yes – a sponge filter keeps the water clean.
Do Sponge Filters Add Oxygen?
Despite the lessened capacity for surface agitation, sponge filters offer plenty of gas exchange due to the constant flow of air bubbles. So, it transfers and exchanges enough oxygen and carbon dioxide for fish and plants, respectively.
Does Sponge Filter Clean Fish Poop?
Yes, a sponge filter can catch and trap fish poop, as well as leftover food and decaying plants. However, a sponge filter might not be effective if you have an animal like a goldfish or a turtle that poops a lot.
How Long Does Sponge Filter Last?
A sponge filter can last anywhere between a few months to a couple of years, depending on TLC you offer it.
Final Words: Are Sponge Filters Good?
Sponge filters are underdogs. They have all the qualities required for efficient filtration but often end up on the back burner.
As we discussed above, a good sponge filter’s benefits range from strengthened biological filtration and economic advantage to producing gentle current and quiet operation.
If you have a big tank – for example, a turtle tank or a goldfish tank – a sponge filter might not be enough. But if you have a small- to medium-sized tank, it’d make a great choice.
I use sponge filters in my hospital tank, quarantine tank, and breeding tank, and they’re worth every penny.