The Smallest HOB Filter for Small Guppy Tank

No fish tank is complete without a good filter. You’ll need one to keep the water fresh and to neutralize harmful compounds like ammonia or nitrites. The same remains true, whether you have a 100-gallon tank or just a 5-gallon nano-tank. But finding a good filter becomes problematic when you go for smaller tank dimensions or for a fishbowl.

I know because I’ve dealt with this issue in the past. It can be frustrating and the search for the perfect filter is time-consuming. That’s why I want to help other new aquarium hobbyists to set up their small tanks. In this article, I’ll talk all about my personal favorite small HOB filter. If you’re searching for a HOB filter for your guppy nano-tank, look no further! This is the saving grace we’ve all been waiting for!

Meet The AquaClear HOB Filter

Now, there are obviously many great HOB filters for smaller tank sizes. But I can only speak from personal experience here. Out of all the small HOB filters I’ve tried so far, the AquaClear was the only one to meet all my expectations. There are many reasons why I consider this to be a top-shelf product.

First, this filter comes in a variety of sizes to match multiple tank capacities. Whether you have a 5-gallon or 100-gallon tank, the AquaClear has you covered. The smallest HOB filter from this line is the AquaClear 20, suitable for tanks holding 5-20 gallons of water. It’s a great, economical choice for small tanks.

The AquaClear 20 is light, compact, and easy to set up, even for a complete beginner. It has low energy requirements, approximately 6 watts, and an output of up to 80 GPH. Another great plus is its adjustable flow rate system. This makes the AquaClear highly versatile, as you can adjust the output for any tank size up to 20 gallons.

Last but not least, this product has a three-stage filtration system, thanks to its diverse filter media. At the bottom, there’s a sponge filter that helps with removing waste and other debris, as well as with biological filtration. For chemical filtration, the activated carbon takes on the job of removing heavy metals, toxins, tannins, and other sources of discoloration.

On the top part of the filter, there are ceramic rings that help neutralize harmful ammonia and nitrites. These rings are a form of biological media. They provide a large surface area which promotes bacterial growth. But we’re talking the good kind of bacteria here. These bacterial colonies are crucial for completing the nitrogen cycle in your tank.

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AquaClear HOB Filter For Fry Tanks

As I’ve already said, the AquaClear 20 filter is a great match for tanks of anywhere between 5-20 gallons. Thanks to its adjustable flow rate and its compact design, you can install this filter on even the smallest aquarium. In my opinion, this HOB filter is even a great choice for a nano-tank.

But besides matching aquarium dimensions, you might be wondering: “Is this filter safe for a fry tank?” Guppy fish are already small and delicate, but the tiny fry are particularly unsafe around tank equipment such as filters or aerators. So, is the AquaClear the right choice for a guppy tank? I would say yes. In fact, this filter is even ideal for a fry tank.

Because you can adjust the flow rate at any time, this filter won’t be too powerful. Another big bonus is the built-in safety measure for the intake tube. As small fish approach the intake tube, the filter can easily suck them up if the flow is too powerful. But this tank’s tube comes with a grid. This will prevent your guppy fry from accidentally finding its way into the tube.

Aqua Clear HOB Filter Maintenance

There’s only one thing you have to do to keep this device running smoothly. You have to clean it regularly. But don’t worry, this filter is as easy to clean, as it is to set up. The entire process takes 10 minutes at most, and it should be done at least once a month. That’s hardly high-maintenance if you ask me.

To clean the filter, you must always unplug the device first. Under the cover, you’ll find the filter basket which contains all the filter media in a particular order. The order should always be the following: sponge filter on the bottom, the activated carbon in the middle, and the ceramic rings on top.

Whenever you clean the filter media, remember to always keep the activated carbon and ceramic rings in aquarium water. Never use tap water on these two components. Tap water is the last thing you should be using on your ceramic rings. Remember, ceramic rings are biological filters. You need to keep the beneficial bacteria on these rings alive, and chlorinated tap water will do the exact opposite.

Aquarium water is enough to rinse any dirt accumulated on the carbon and ceramic filters. You can rinse the sponge filter using tap water, or aquarium water. Apart from filter media, you should also thoroughly clean the intake tube and the impeller using lukewarm water and either a small brush or a cloth.

After you’re done, all that’s left to do is to assemble the filter and plug it back in. Always remember to place the filter media in the original order. After setting everything up, the filter should be back to work in a few seconds.

When To Replace Filter Media?

After some time, you might notice your filter isn’t doing its job as well as it used to. That’s to be expected. Like anything else, filter media get used up and they won’t be as efficient as they once were. When this happens, you’ll have to replace them with new components. But how often should you do that?

This depends. If you have many guppies producing lots of waste, the filter will be working harder. And the more you have to wash the filter, the shorter its lifespan. If you have a small-sized tank with just a few fish, then your filter will likely last a lot longer. The manufacturer offers some conservative suggestions.

According to them, you should replace the carbon every month, while the sponge and the ceramic rings will last for two and three months respectively. I think that’s a bit excessive. I wouldn’t personally replace the sponge or ceramic filters unless they got damaged in some way. These filters offer biological filtration, and it takes some time for the beneficial bacteria to build up on these surfaces.

Every time you replace them, you’re basically starting over. So new sponges and ceramic rings are actually doing a worse job than older ones. The only thing I’d replace is the activated carbon. This type of filter media does run out, especially if you have a large aquarium. For smaller aquariums with fewer fish, the carbon filter can last a lot longer than a month. If your fish don’t produce excessive waste, and if you keep your aquarium and water clean, you can keep the same carbon filter for up to a year.


Finding a small HOB filter for a nano-tank is difficult. While more and more products are emerging to meet the growing demand, not all of them are of good quality. And while I can’t speak about all the HOB filters on the market, I can say the AquaClear was the best one I have used so far.

I think this compact, versatile filter has everything a fish keeper could wish for. And it works great for smaller tanks. It doesn’t take much space, and you can easily turn the water flow up or down, depending on your aquarium size. The three-step filtration system is also great for tanks with lots of fish.

And this filter is also safe for fry tanks, which is a big bonus. I wholeheartedly recommend this filter for anyone interested in small aquariums. I’m also open to suggestions! Have you ever tested any small HOB filters? Do you have any favorites or recommendations? Let me know!

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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