Even though a sponge filter is probably the simplest way to filter your aquarium you can, on occasion, run into a problem. Sponge filter issues are generally easy to fix once you’ve identified the cause.
Experiencing a problem with the running of your aquarium sponge filter can be caused by several different things. For example, it could be a faulty air pump, a blockage in the air line, or excess debris build-up in the sponge itself. It can also be caused by not having a large enough sponge for the tank capacity. Or even an air pump that’s not powerful enough to provide the right amount of filtration for your aquarium. There are other possible reasons too, but these are probably the most common ones.
Let’s take a look at the most frequently asked questions when it comes to sponge filter issues.
And, more importantly, let’s get some answers to solving the problem too.
Why Is My Sponge Filter Not Bubbling?
Bubbles are an important part of how a sponge filter works. The bubbles created by the air being forced through the sponge filter’s openwork stem is what makes the sponge suck in, and trap, the debris from the water column.
No Bubbles = No Filtering
So if your sponge filter isn’t bubbling you need to find out why so that you can get your sponge filter going again.
Here’s a check list to help you identify and fix the problem
- Check The Air Pump – Check that the air pump is working properly. If the pump isn’t up to speed, or not working at all, you won’t get any air through the tube to operate the sponge filter. If it’s a faulty pump you’ll need to replace it as soon as possible or you will lose your fish and their tankmates.
- Check For Blockages – If the pump is working fine the next thing to do is to check the air line tubing for blockages. While it’s unusual for a blockage to happen in an air line tube it’s not impossible. So take a good look at it. If you spot a blockage clean it out or replace the air line tubing.
- Check The Air Line Tube Attachment – Air line tubes can become dislodged during sponge filter maintenance. So double check that the tube is securely attached to the air inlet ‘nipple’ just in case it’s loosened up and is not fully attached.
- Check The Check Valve – It’s always best to have a check valve on your air line tube to stop water from syphoning up and into the air pump when the power is off. If you’re setting up your sponge filter for the first time and it’s not bubbling, check that you have the valve the right way round. It’s usually coloured end pointing down away from the air pump. But read the instructions that came with your check valve. If you’ve been running your sponge filter successfully for a while check that there are no blockages in the check valve. If there is then clean it out. Or replace it with a new one.
Tip: Only ever rinse out your Sponge Filter sponge in the used aquarium water that you’ve syphoned off as part of your tank maintenance. If you rinse the sponge out in tap water you will kill off all the beneficial bacteria that has grown inside it.
Why Isn’t My Sponge Filter Sucking In The Mess?
If you think that your sponge filter isn’t doing a good enough job in keeping your tank water clean there could be a few reasons for this. It might be a problem with the size of the sponge, the strength of the air pump or even where the sponge filter is positioned. There are other things too that can stop your sponge filter from doing its best.
Let’s take a closer look at what can make a sponge filter inefficient.
- Sponge Filter Size – If your sponge filter isn’t large enough for the water capacity of your aquarium, and also the amount of fish etc that you keep, it won’t be able to cope. If it can’t cope with the water volume and the mess produced it won’t be able to keep the water clean. So it’s important to get some advice on which sponge filter is going to be the best one for your needs.
- Air Pump Capacity – Just like getting the size of your sponge filter right, you need an air pump that’s powerful enough to process the amount of water in your aquarium. If your pump isn’t able to constantly shift the volume of water in your tank it won’t be capable of running your sponge filter effectively. So be sure to get one that’s powerful enough to do the job. Again, get some professional advice on this.
- Positioning Your Sponge Filter – Where you place your sponge filter in the tank can make a big difference. This will depend on the size of your tank and how messy the tank inhabitants are. It’s often a case of trial and error to find the best place for your sponge filter to work at its best. But it’s worth experimenting a little.
- Sponge Filter Maintenance – Sometimes it’s something as simple as a clogged dirty sponge that’s causing the problem. So keep on top of your regular tank maintenance. This includes squeezing out your sponge in the tank water that you’ve syphoned off.
- Check For Wear – Sponges don’t last forever so it’s important to check for wear and damage every time you carry out your tank maintenance. If you need to replace the sponge it’s best to build up the good bacteria in the new one before you use it as your main filtration. You can do this by running the new sponge in the aquarium for a few weeks. You’ll need to keep the old sponge filter running at the same time as well until the new sponge is ready to replace the old one.
Tip: If you’re using a double sponge filter in your aquarium, and both of the sponges need replacing, only replace one at a time. Let the new sponge run for a few weeks before changing the other one. This way you’ll have one mature sponge that’s full of beneficial bacteria running at all times.
Why Is My Sponge Filter Floating?
It’s not unusual for a new sponge filter setup to float. Until the sponge is completely soaked and heavy with tank water, and at least some debris, it naturally bobs about in the water.
Which isn’t usually what any fish keeper wants.
If it doesn’t bother you too much though, you can just let it float for day or so until it sinks of its own accord.
Or you could anchor it down buy clipping the air line, without squashing it, to the top edge of the aquarium. At least that way the sponge filter won’t be able to float too far.
Another option is to add a sucker to the sponge so that it suckers to the inside of the glass and keeps it in place. You can use superglue gel to attach the sucker to the sponge because it’s an aquarium safe glue.
You can also weight the base down by putting aquarium rocks, stones or gravel, on top of the base to keep it on the substrate until it stays there of its own accord.
As you can see, there are several ways to keep your sponge filter anchored while it’s in the process of weighting itself down.
How Can I Make My Sponge Filter Quieter?
Because sponge filters are run by an air pump that makes lots of bubbles there’s going to be a certain amount of noise. You can make your sponge filter quieter by adjusting the air flow, reducing the size of the bubbles or just simply by using a quieter air pump. There’s also a few other easy solutions.
Adjusting the air flow is only an option if you have an adjustable air pump. Not all air pumps are like this. Mine for example, are just either on or off. But if you can adjust the flow on your air pump you’ll be able to turn it down a little and slow the amount and speed of the bubbles that are coming from your sponge filter. Fewer bubbles means less noise.
Just be careful that the reduced air flow is still producing enough filtration for your aquarium. You’ll probably have to experiment a bit to find a happy medium.
Reducing the size of the bubbles is another option. And it’s an effective one. If your sponge filter allows you to add a short piece of air line inside the central openwork core you can put an air stone/diffuser on the end of it.
The air stone/diffuser makes the bubbles smaller and quieter.
You need to make sure there’s a gap between the bottom of the air stone and the base of the sponge filter for it to work well.
You can use this method even if your air pump isn’t adjustable. In fact it’s a good way to reduce the bubble noise if you can’t adjust the air flow.
Buying a quieter air pump, if the pump you’re using is a noisy one, is definitely a quick fix. And there are plenty of air pumps available that have different filtering capacities and are marketed as low noise.
The Nano pump that runs the sponge filter in my tiny Cherry Shrimp tank is a Love Fish Nano Ultra Quiet Air Pump (Max 25 Litre Capacity). And believe me, you can’t hear it at all. The only thing I hear is the gentle bubbling of the sponge filter itself. If you’re in the UK you can get it from Pets At Home but if you’re buying online or from another country then this similar one here
can be found on Amazon as the exact one I have isn’t for sale on Amazon.
So if your air pump is driving you crazy take a look at getting a quieter one.
And there’s a couple of other things that help to reduce the noise of your sponge filter.
Adding a lid/hood to your tank helps to block out some of the bubble noise. It also helps to reduce the amount of water that ends up on the surface that your aquarium is sitting on.
Putting a mat under your tank helps to deaden the vibration and noise. I’m using the term ‘mat’ loosely because you can use different things that will do the same job.
You can literally use an off-cut of carpet/mat if you like. But there are other options too.
Carpet/laminate flooring underlay will have the same effect. Or you can even use an old bath towel under the tank to help keep things a little quieter.
I’m sure you’ll come with some other ideas of your own that will do the trick.
Tip: If you don’t have a spare air pump and line to prep a replacement sponge in your tank, soak the sponge in some syphoned off tank water and fish poop. This will help get the beneficial bacteria off to a good start in the new sponge. Keep an eye on your Nitrite and Nitrate levels over the next couple of weeks though just in case of a spike.
Does A Sponge Filter Need To Be Fully Submerged?
A sponge filter is an internal filter, and like all other internal aquarium filters, it needs to be fully submerged in the water for it to work. The best position for a sponge filter is sitting on top of the substrate at the bottom of the tank. Although the air pump that drives it needs to be well out of the water for safety.
I’ve added this question because if you’re unfamiliar with sponge filters you’re going to want to know where it should sit in your tank. Just like any other kind of aquarium filter knowing where to place your sponge filter is vital to how efficiently it’s going to work.
So whether your sponge filter is one with a weighted base, one that has suckers to attach it to the glass, or even one that you’ve put together yourself, you need to place it at the bottom of the tank.
The lower down it is, the better it will filter your tank water.