6 Reasons to add sponge filters to your aquarium today

6 Reasons to Add Sponge Filters to Your Aquarium

When you start thinking about ALL of the equipment you need for your saltwater aquarium, it’s easy to overlook the little things – for instance, sponge filters. Everyone needs them around – and knows they’re necessary in the back of their mind – but the handy pieces of filter media can get overlooked. You may even feel sponge filters aren’t a big priority. And that’s where you’re missing a big opportunity to get your reef tank running efficiently. Don’t believe me? Well, that’s where these six handy reasons will come along and convince you otherwise!

Table of Contents: Why You Need Sponge Filters in Your Aquarium

Behold, the humble sponge filters! If you’ve never stopped to think about what they can do for your saltwater aquarium, just look at these links. They offer plenty of intriguing thoughts on the possibilities this little (or not so little – it depends on your tank size) piece of equipment can provide. If you want all of the reasons you should stock up, read through the entire list. Or you can pick and choose from the ideas that appeal the most. Either way, you’re going to want to install these filters, and your fish and invertebrates will thank you.

What is a Sponge Filter?

Before we dive into all of the reasons you’ll want to have sponge filters in your aquarium sump (or elsewhere – and, don’t worry, we’ll tackle that, too), let’s start with the basics. A sponge filter is a mechanical AND biological filtration option that works with pumps, powerheads, and as part of other filter types. You start with (you’ll never guess) a sponge.

Aquaneat Aquarium Sponge Filter

Depending on the size of the pores (holes), you can remove different waste as water passes through. Meanwhile, all of the extra surface area allows bacteria somewhere to colonize. And that means you start to develop biological filtration the longer the sponge sits in place. All of those pores, nooks, and crannies can add up to a thriving bacteria colony. And that means plenty of active filtration – all in one handy piece of equipment.

Sponge filters come in different sizes, shapes, and even pore dimensions. They work for plenty of reef tanks and sumps, making them an ideal choice for any hobbyist. And as we dive into those top six reasons, you’ll see why you want to keep two sponge filters running at all times.

Ready to get on with the list? Then let’s go!

1. Expanding Your Biological Filter

So we’ve talked about the sponge filter and the additional surface area you get. As the sponge “matures,” bacteria find a home within the pores and along the surface of the synthetic material. All of those colonies of beneficial bacteria go to work as part of your tank’s biological filter. And you don’t even need to purchase an extra piece of equipment in the process! Those bacteria help control the ammonia and nitrate levels within the aquarium, reducing your need to fuss around with constant water testing.

Even better, you don’t need to DO anything! Once you install those sponge filters, the process happens naturally. Bacteria from your miniature ecosystem find their way to the filter and take care of things on their own. It’s a way to “install” a biological filter without any hassle or work (not to mention an added expense).

2. Caring for Sick or Injured Fish

Let’s face it: Bullying and aggression happen. You also need to cope with fish getting too close to pumps and ending up injured. If you leave the wounded fish in your display tank, you’re inviting possible infection. Bacteria find their way into the site of the injury and turn into a problem. Then you end up with a sick that’s severely ill – and potentially carrying around something they can pass to their tank mates.

Having sponge filters in your sump allows you to set up a “hospital tank” to nurture those injured animals back to health. And because you already have healthy colonies of bacteria working to keep the tank clean and cycled, you won’t take any risks associated with new tank syndrome.

All you need to do is shift your convalescing fish over while you work on treating them. The beneficial bacteria “scrub” away the nuisance pathogens while your fish enjoys a break from its neighbors. And there’s no risk of high ammonia levels. Because your sponge filters never let those wastes roller coaster out of control.

(Okay, so you and I both know that jawfish isn’t ACTUALLY sick. It’s still pretty funny and worked too well to pass up.)

3. Preparing For New Purchases

Admit it: you get that “gotta have it” feeling when you stop into your local fish store or get that sale email from your favorite online shop. You spot a fish or coral you’ve been dreaming of, notice a sudden sale (that won’t last), and you don’t have your quarantine tank set up. Even worse, you can’t get it all set up and wait for it to cycle before that sale vanishes (or someone else snatches up the fish). And adding the fish or coral to an uncycled quarantine tank or the display tank and “hoping for the best?” You know that spells disaster.

Multiple sponge filters make it easy to get new aquariums ready to go

That’s where those sponge filters come in handy. As long as you’ve run sponges through your sump or aquarium for at least a month or two (or more), you have “mature” colonies of bacteria living inside. In a matter of moments, you can move the filter into your quarantine tank, providing a ready-to-go stock of healthy, beneficial, CYCLED bacteria. They go to work on those water conditions immediately, smoothing everything out as your fish acclimate.

Instead of fretting over getting your tank ready over weeks, you can have it ready to go in no time. And all you need to do is have sponge filters running in your sump or display tank ALL THE TIME. Then you can pick them out and transfer them. Simple as can be. (And it supports those impulse purchases everyone’s guilty of)

4. Speeding Quarantine

Remember at the beginning of the article, when I threw out a suggestion of TWO sponge filters? Not a typo (and not because I’m a fan of buying in bulk – though that DOES help you save money in the long run). Nope, there’s a method to that madness. Having two filters mature and ready at all times is the most efficient way for me to continually add new saltwater fish to my display tank. I’m DECREASING quarantine time without putting my fish at risk.

It sounds crazy, but I promise it works. And it’s because of those two sponge filters. Here’s how it works:

  1. When my display tank is stable, and I haven’t purchased a new fish or coral in a while, I shut my quarantine tank down. I dry it out and let it “rest” rather than run it empty. That cuts down on noise, maintenance, and electrical costs.
  2. Then when I buy a new fish or coral, I do a partial water change in the display tank and use the wastewater to fill ~75% of the quarantine tank. I top off the rest with newly made saltwater (that provides a 25% water change right away).
  3. I grab the sponge filter from my sump and get the tank up and running, complete with conditioned water and an active, cycled biological filter.
  4. After my fish or coral finishes their quarantine, I clean out and dry the tank again (this prevents unwanted critters from sticking around). I don’t want to return the sponge filter to the display tank, so I also clean it with freshwater and dry it.
  5. Then I start my quarantine tank over the way I did the first time. And I replace the clean, dry sponge back in the sump, so it’s ready in a month for my next cycle.

Voila! Those sponge filters save me time on the quarantine process. And keeping two ready at all times means I don’t have to delay my purchases. (See how #3 flows nicely into this reason?) It’s a handy trick that allows you to keep your fish and coral moving around.

5. Anticipating Emergencies

No one WANTS their tank to cope with problems. However, things go wrong all the time. You might cope with power failures. Or what if your return pump burns out? If you don’t have a backup pump in the house, or even if you DO but have to run to work when it breaks, sponge filters might provide “life support” in the interim. You go it, those little clumps of synthetic pores will continue to provide the biological filtration your tank desperately needs – even WITHOUT electricity.

Bacteria don’t run on power. Granted, the amount of water flowing through the filter goes down without the aid of the pump. But as long as you have mature sponge filters, those colonies will happily go about their business as wastes hit all of that surface area. It buys you time in an emergency. And if you plan FURTHER ahead (or have already coped with the trauma of a power failure and learned your lesson) and buy a battery-operated air pump, too,  you’ll be ready to oxygenate and remove wastes from your tank.

6. No New Tank Syndrome

One of the biggest problems hobbyists face is new tank syndrome. The excitement of setting up that first aquarium, complete with dazzling fish and corals, overwhelms new aquarists, and they rush that crucial cycling step. Suddenly, they’re watching their fish pass away in record numbers. It’s heartbreaking – and easy to avoid.

You have two sponge filters in your sump (of course you do). And you can eliminate new tank syndrome in your zip code by allowing anyone starting their saltwater tank to borrow a sponge. All of that beneficial bacteria will help them jump-start their reef tank. You’re providing a healthy, thriving biological filter that will get their wastes and ammonia under control. Then their fish won’t suffer the fate of an early demise.

You’ll earn yourself the position of instant hero. You might even get a street named after you. (Legal notice: Actual results may vary. Please don’t anticipate getting a street named after you)

Working With Sponge Filters

Now that you’re excited about purchasing sponge filters (remember, you want two) and using them in your tank, let’s do some clarification. Because you might feel overwhelmed about the extra equipment needed to run these handy tools. And using and operating these sponges isn’t that complicated.

First, you don’t need to “set up” sponge filters. By this, I mean you don’t NEED to actually hook them up to an air pump. If you want to make them bubble away in your sump, it helps, and it’ll improve the oxygen flow in your aquarium. However, there’s no reason to run around looking for an air pump. Assuming you get reasonable water flow through your sump, your sponge filters will naturally colonize with beneficial bacteria no matter what.

Second, you want to “clean” your sponge filters every few weeks. This means submerging them in the used water when you perform your water changes and giving them a few gentle squeezes to get rid of the bigger pieces of waste that collect on the pores. If you don’t, you’ll end up with clogs. Clogs mean the mechanical part of the filtration won’t work. You could also end up with some UNWANTED bacteria attaching to the waste. (Do the same if you’re moving the sponge to another tank)

Sponge filters come in different sizes

Don’t clean both sponges at the same time. Choose one the first week, then do the other next time. If you tackle all of your sponge filters at once, you WILL compromise the biological filter. It’ll lead to a spike in the ammonia after the cleaning as the bacteria recover.

Third, if you don’t have a sump, you can still use sponge filters. Stash the sponge behind the live rock in your display tank. Those pores will attract beneficial bacteria no matter WHERE they are. And they’ll get water flow courtesy of the movement of water in the tank. You won’t have to look at the filter, but it will still be there and ready when you need it.

For More Information

Maybe you’re still not convinced of all the good sponge filters can do for you. That’s okay. There’s still some more information out there to bring your over to the sponge side. (Though, really, winning the adoration and gratitude of your hobbyist peers should do the trick)

First, how about taking a look at this YouTube video on everything you could possibly want to know about sponge filters:


Want to further explore everything you can do with sponge filters?


For a small amount of money, sponge filters in your tank do PLENTY. All of that extra biological filtration capacity provide opportunities everywhere you look. I only threw out six reasons that I came up with off the top of my head. When you start thinking about what you can do with healthy cycling tanks, you can probably come up with even more. So, why not take a moment to get prepared today. Add a couple of sponges to your shopping cart today.

6 reasons to add sponge filters to your aquarium today






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