The Best 5 Gallon Aquarium Filter: Internal, HOBs & Small Canisters

Keeping your water clean and clear is key in a small 5 gallon fish tank. So take a look at our guide to help you find the best 5 gallon aquarium filter for your needs!

By Matt Thomas
Last updated on

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best 5 gallon aquarium filter

A 5 gallon aquarium is a great way of bringing your aquatic pets into a small space, like your office or bedroom. And choosing the best 5 gallon aquarium filter is critical to making sure your water is clean and safe for your fish.

We spent many combined hours assessing the best 5 gallon aquarium filters and found the AquaClear 20 Fish Tank Filter to be the best choice overall. As it’s a hang on back filter it provides great filtration without taking up valuable space in your tank.

But there are several different types of filters to suit your 5 gallon aquarium, from internal filters to small canisters. That’s why we’ve included reviews from these different categories to help you find the right one.

  1. Best Overall: AquaClear 20 Fish Tank Filter
  2. Best For Value: Marineland Penguin 75 Bio-Wheel Power Filter
  3. Best For Budget Internal: Aqueon Quietflow E10 Internal Power Filter
  4. Easy Maintenance Internal: Tetra Whisper Internal Filter
  5. Best Slimline HOB: Marina S10 Power Filter
  6. Best For Low Current: AQUANEAT Aquarium Bio Sponge Filter
  7. Best Small Canister: Zoo Med Nano 10 External Canister Filter

Best 5 Gallon Aquarium Filter Reviewed

Choosing the best 5 gallon aquarium filter is often a balance between one that’s compact enough for your tank, but also has the right flow rate and capacity. We’ve covered all this and more below to help you make the right choice.

1. AquaClear 20 Fish Tank Filter

AquaClear 20 Hang On Back Filter

Photo: Chewy.com

  • Filter Type: Hang On Back
  • Dimensions: 5.0 (w) x 4.0 (d) x 6.25 (h) inches
  • Flow Rate & Aquarium Capacity: 100 GPH, for 5 to 20 gallon tanks
  • Filter Media: 3 stage filtration – foam for mechanical, carbon for chemical, and BioMax rings for biological filtration
  • Best For: Overall

The AquaClear 20 hang on back filter is an excellent choice for a 5 gallon fish tank, and is our top pick overall. At 5.0 x 4.0 x 6.25 inches it’s really compact, and will sit neatly on the back of a standard 21 x 14 x 18 inch 5 gallon tank, leaving the maximum swimming space for your fish.

Although it’s small it’s incredibly powerful with a flow rate up to 100 GPH. But for a 5 gallon tank you can adjust it right down, as much as 66%, with the easy to use switch on top. This means you can cycle all your water over 6 times an hour, perfect for keeping it clean and clear.

Plus with AquaClear’s ‘refiltration’ system, when you select the low flow rate up to 50% of the water recirculates inside the filter. This means longer contact time with your filter media, and results in cleaner water overall.

Many owners report that the AquaClear is also super quiet and really easy to access and customize with your own media. And with up to 7 times the filtration volume of similar filters, the AquaClear is a compact but powerful choice for a 5 gallon tank.

2. Marineland Penguin 75 Bio-Wheel Power Filter

Photo: Amazon.com

  • Filter Type: Hang On Back
  • Dimensions: 5.31 (w) x 5.0 (d) x 7.56 (h) inches
  • Flow Rate & Aquarium Capacity: 75 GPH, for tanks up to 10 gallons
  • Filter Media: 3 stage filtration consisting of Rite-Size A cartridge (mechanical, chemical) and bio-wheel for wet/ dry biological filtration
  • Best For: Value

The Marineland Penguin 75 is a great choice if you’re on a budget but want a powerful filter for your 5 gallon tank. At 75 GPH it will cycle your water up to 15 times an hour, that’s around 3 times the minimum amount needed so is great for over filtration to get your water ultra-clear!

One drawback though is the flow itself is not adjustable, so this is not the filter to choose if you have a betta fish. You can, however, adjust the intake strainer to divert it from the bottom of the tank to the middle. This helps if you have bottom dwellers and need to reduce the current.

Mechanical and chemical filtration is provided by Marineland’s Rite Size A cartridge, which easily lifts out making maintenance easy. And the spinning bio-wheel makes contact with the air and water, allowing beneficial bacteria to colonize rapidly providing great biological filtration.

While some owners have reported issues with the bio-wheel not turning and making noise, it’s often a case of re-reading the instructions. Our tip is to make sure the impeller is properly located and you should find it very quiet during operation.

3. Aqueon Quietflow E10 Internal Power Filter

Photo: Amazon.com

  • Filter Type: Internal
  • Dimensions: 4.69 (w) x 3.75 (d) x 6.31 (h) inches
  • Flow Rate & Aquarium Capacity: 60 GPH, for tanks up to 10 gallons
  • Filter Media: 3 stage filtration – Filter cartridge (mechanical and chemical) sponge (mechanical) biological cartridge holder (biological)
  • Best For: Budget Internal

The Aqueon Quietflow E10 looks a little like a HOB filter, but it’s actually internal as it hangs inside your tank. But at only 4.69 x 3.75 x 6.31 inches it’s compact enough to sit in your 5 gallon aquarium while still leaving plenty of room for your fish.

At 60 GPH, the E10 is powerful enough to cycle your 5 gallon tank up to 12 times an hour, so more than twice the minimum needed to keep your water in excellent condition. Note that the flow is not adjustable though, so we’d recommend alternative filters for a betta fish.

The Aqueon Filter Cartridges are dual-sided with activated carbon and dense floss giving excellent mechanical and chemical filtration for a 5 gallon tank and removing debris and toxins from your water. They are also really easy to change by simply flipping up the filter’s lid.

Overall this is a powerful filter which will keep your 5 gallon tank clean and clear, and many owners praise for it’s ultra-quiet operation and ease of use.

4. Tetra Whisper Internal Filter

Photo: Amazon.com

  • Filter Type: Internal
  • Dimensions: 3.0 (w) x 3.0 (d) x 7.38 (h) inches
  • Flow Rate & Aquarium Capacity: 27 GPH, for tanks up to 4 gallons (although can be used for 5 gallons)
  • Filter Media: Whisper Bio-bag with 3 stage filtration
  • Best For: Easy Maintenance Internal

While the Tetra Whisper Internal Filter is designed for aquariums up to 4 gallons, we recommend it for 5 gallon tanks too, and many owners agree. 

The 27 GPH flow rate is not adjustable, but it can cycle all your water just over 5 times an hour which is right in the range needed to keep your 5 gallon aquarium toxin-free. And at 3.0 x 3.0 x 7.38 inches it’s compact enough to sit in the corner leaving plenty of room for your fish.

You do have the option of the Whisper 10i designed for tanks up to 10 gallons. But in contrast, it’s a bigger filter for a 5 gallon aquarium at 4.25 x 4.0 x 8.0 inches. And its 80 GPH flow rate will cycle a 5 gallon aquarium 16 times an hour which can be a little powerful.

The Whisper 4i uses small Whisper Bio-bags which are really easy to change by lifting the hinged lid. In fact, this is one of the easier small filters when it comes to maintenance.

Many owners report this is a quiet but powerful filter, and several love the smaller size as it’s nice and compact for their 5 gallon aquarium!

5. Marina S10 Power Filter

Marina S10 Hang On Back Filter

Photo: Chewy.com

  • Filter Type: Hang On Back
  • Dimensions: 6.50 (w) x 3.70 (d) x 7.30 (h) inches
  • Flow Rate & Aquarium Capacity: 55 GPH, for tanks up to 10 gallons
  • Filter Media: Bio-Carb cartridge for mechanical and biological, Bio-Clear zeolite cartridge for chemical filtration (sold separately)
  • Best For: Slimline HOB

The Marina S10 is a slimline hang on back filter that’s another great option for your 5 gallon tank. Its 3.70-inch depth means it only protrudes about 2 inches from the back of your tank, so perfect if you have your aquarium on a desk and need to position it close to the wall.

Its 55 GPH flow rate will cycle your 5 gallon tank up to 11 times an hour, which is great if you have a higher bioload and need to over filter your water. But it’s also fully adjustable so you can lower the current for fish with delicate fins.

Unlike many HOB filters, the S10 has its motor positioned on the intake tube rather than in the main unit. While this takes up a tiny amount of tank space, having the motor submerged in your tank makes this filter extra quiet.

Marina produces cartridges including Bio-Carb with Ceramitek to help colonize beneficial bacteria, and Bio-Clear containing zeolite to absorb ammonia. While these can be expensive, you can add your own biological or other types of media to customize it to your needs.

Overall many owners praise this filter for its quiet operation and ability to customize your media.

6. AQUANEAT Aquarium Bio Sponge Filter

Photo: Amazon.com

  • Filter Type: Sponge
  • Dimensions: 2.0 (diameter) x 4.75 (height) inches
  • Flow Rate & Aquarium Capacity: Flow dependent on external pump (sold separately), for tanks up to 10 gallons
  • Filter Media: 2 stage filtration – Bio sponge for mechanical and biological filtration
  • Best For: Low Current

AQUANEAT’s Aquarium Bio Sponge is a compact little sponge filter that’s a fantastic pick for your 5 gallon tank if you have a couple of nano fish, shrimp, or some baby fry. With a 2-inch diameter and 4.75-inch height, it will take up minimal swimming space in your tank.

You’ll need an air pump to run it (sold separately), which will not only draw water through the sponge to filter debris, but will also create plenty of bubbles to oxygenate your tank. This helps maximize oxygen uptake for your fish and keep them healthy [1].

The sponge is also a very safe option for small fish as there’s no filter intake for them to get sucked into. And it’s easy to remove the sponge and rinse with aquarium water, making maintenance easy and hassle-free.

Many owners give this little sponge filter great feedback for keeping their water crystal clear, being simple to maintain, and producing a low flow, making it great for delicate fish like a betta.

7. Zoo Med Nano 10 External Canister Filter

Photo: Amazon.com

  • Filter Type: Canister
  • Dimensions: 4.8 (w) x 5.8 (d) x 11.3 (h) inches
  • Flow Rate & Aquarium Capacity: 80 GPH, for tanks up to 10 gallons
  • Filter Media: 3 stage filtration – customizable media chamber with mechanical filter sponge, bio-ceramic filtration media, and carbon chemical filtration media included
  • Best For: Small Canister

The Zoo Med Nano 10 is an excellent little canister filter for a 5 gallon aquarium, and as it’s external it won’t take up any room in your small tank.

It’s listed at 80 GPH, but we found it’s actually closer to 30 to 40 GPH, which is in line with customer reviews too. But for a 5 gallon that’s actually plenty as it will cycle your water around 6 to 8 times an hour. More than enough for a 5 gallon tank to be clean and clear.

While the Zoo Med Nano comes with filter sponge, ceramic media, and carbon, the large media chamber is fully customizable. So you can add the best biological, chemical, and mechanical media to ensure your water stays toxin-free.

Although the flow is not adjustable, you can choose to use the output nozzle or spray bar provided. Using the spray bar not only helps reduce strong currents, but also agitates and oxygenates your water to provide a healthy environment for your fish.

This filter is ultra-quiet when running, and also has suction cups on the bottom which further reduce vibration and make it virtually silent. Many owners praise this filter for its customization, quiet running, and ability to get their water nice and clear.

Why Do 5 Gallon Aquariums Need A Filter?

Your fish excrete ammonia directly from their gills and in their feces [2]. Ammonia is highly toxic and can cause death if left to build up in your tank. And the build-up of ammonia, nitrites, and nitrates happens a lot quicker in a small 5 gallon fish tank than in a larger aquarium.

white fish on black background

If you didn’t have a filter you could technically reduce the build-up of these toxins by just doing water changes. But it’s a lot more difficult, and you’d need to do them every few days. With the right filter, this maintenance can be much less frequent and more manageable.

How Do Aquarium Filters Work?

As well as other benefits like aerating and oxygenating your water, a filter keeps it clean by pumping it through 3 main media stages:

  • Mechanical Filtration: The first stage in most filters is mechanical. Filter pads, sponge, or floss trap debris, and particulates from the incoming wastewater. This not only clears the water but also stops debris from clogging the other types of media in your filter. 
  • Biological filtration: One of the most important stages, biological filter media such as ceramic rings, is designed to provide a home for beneficial bacteria to colonize. It’s these bacteria that break down harmful ammonia as part of the nitrogen cycle
  • Chemical filtration: Substances such as activated carbon and zeolite are often used as part of chemical filtration [3]. These absorb ammonia and other toxins, helping to keep your water parameters under control.

Best Types Of Filter For A 5 Gallon Tank

Many of the best 5 gallon fish tanks come with built-in filters, but if yours doesn’t there are plenty of different types to choose from. We’ve covered some of the best 5 gallon aquarium filter options below.

Hang On Back (HOB) Filters

HOBs (aka power filters) are really popular for tanks of all sizes. As the main body of the filter hangs off the back of your tank, it makes them great for a 5 gallon aquarium because they don’t take up room inside your tank.

They are also really easy to set up and maintain. Many small HOBs take cartridges with mechanical, chemical, and biological media in one. But you’ll also find you can add your own media in many of them too, meaning you can customize it to suit your needs.

Internal Filters

As the name suggests, these sit inside your aquarium and most contain all 3 stages of filter media often in the form of easy to replace cartridges. While they do take up some swimming space, smaller internal filters are usually quite compact.

So in a 5 gallon tank of around 21 x 14 x 18 inches, for example, a 3 x 3 x 8 inch internal filter can be placed in the corner without taking up too much room.

Undergravel Filters

Undergravel filters sit at the bottom of your tank with the substrate on top. They don’t contain filter media, instead relying on your gravel to act as a mechanical and biological filter as the water is drawn down through it.

While undergravel filters can be a good option for betta tank filtration as they produce a low current, they don’t contain chemical media. And as they use your gravel to trap waste you will have to siphon it regularly as this can build up quickly in a 5 gallon tank.

Sponge Filters

These simple filters can be a great choice for a 5 gallon fish tank, although they can only handle a small bioload and are best if you have a few nano fish, shrimp, or fry. The sponge acts as a mechanical filter trapping debris, and a biological filter allowing beneficial bacteria to grow.

They use a separate external pump to force air through, which sucks the water through the sponge without the danger of sucking up your fish. This has the benefit of producing bubbles to aerate your water too.

Canister Filters

Canisters are generally large, powerful external filters you set up in your aquarium cabinet underneath your tank. Having said that, there are some great options for smaller 5 gallon fish tanks, and because they are external you save more valuable tank space for your fish.

These filters are also customizable meaning you can vary the media to suit your setup. Many have adjustable flow rates which is important in a small 5 gallon aquarium so you don’t produce too much current for your fish.

Tips On Reducing The Flow Of Your Filter

Even with the best 5 gallon aquarium filter, the current may sometimes be a little too high for your fish. If you keep a betta fish, for example, it will need areas of shelter where it can avoid the flow from your filter [4].

There are several ways you can reduce the flow in your 5 gallon tank to ensure your fish doesn’t become stressed: 

  • Pre-Filters: Using a pre-filter or filter sponge over your filter intake can help reduce the current flowing into your filter. This is also good practice in a tank with small fish as it stops them from being sucked into your filter.
  • Buffering: You can place rocks, ornaments, or broadleaf plants like Anubias in front of the filter return to break the flow and create calmer areas in your tank. This will give your fish space where they can rest away from the current.
  • Flow Controls And Diverters: The best 5 gallon aquarium filters, including HOBs, canisters, and internal filters, will have an adjustable flow control to lower the current. Some also have diverters or spray bars that split the flow to reduce current.
blue betta fish in small fish tank

How To Choose The Best 5 Gallon Aquarium Filter

Given the various types of filter you could choose for your tank, let’s now look at some of the key things to consider when choosing the best 5 gallon aquarium filter for your needs.

Aquarium Size And Space

5 gallon fish tanks can come in different styles and shapes. While some can be a standard rectangular prism of around 21 x 14 x 18 inches, others can be a taller, thinner portrait shape. And some can be a peninsula style with a longer width and shallower depth back to front.

It’s important you choose a filter that will physically fit your 5 gallon tank while giving room for decor and swimming space for your fish. HOBs and canisters can be great options as most of the unit sits outside the tank. Smaller sponge and internal filters can be a good choice too.

Filter Flow Rate

The flow rate of your filter is measured in gallons per hour (GPH), and is the number of times all of your tank’s water is cycled through the filter each hour. Freshwater tanks usually need to be cycled at least 4 to 5 times an hour but more is even better.

So for a 5 gallon aquarium, look for a filter with at least a 20 to 25 GPH flow rate. The best 5 gallon aquarium filter should also have an adjustable flow so you can reduce the current for your fish. Many canisters, HOBs, and internal filters will have this feature.

Filter Media

Given that maintaining water quality is harder in a small aquarium, the best option for your 5 gallon tank is to use 3 stage filtration with mechanical, chemical, and biological media. Small filters will often use cartridges with all 3 included, although they can sometimes be costly.

If you own a 5 gallon tank with a single fish like a betta, some shrimp, or just one or two nano fish you may be able to use a simple sponge filter. Just bear in mind that as these filters only have mechanical and biological stages they should be used for tanks with a low bioload.

Minimal Noise Level

Canister filters are often some of the quietest aquarium filters as the external unit is water-driven, rather than air, leading to less vibration. HOBs and small internal filters can also be very quiet when their motor and impeller sit in the water.

Sponge filters can actually be slightly louder than other types due to the vibration of the external air pump. Although the pump for a 5 gallon sponge filter is usually small enough for it not to be too much of an issue.

Ease Of Maintenance

Choosing a filter that’s easy to maintain is important for a 5 gallon aquarium as the limited space can make maintenance tricker. Internal filters, for example, tend to need regular maintenance and you may need to completely remove them from the tank for cleaning.

HOB filters, on the other hand, can be one of the best 5 gallon aquarium filters when it comes to maintenance as you can easily access the media from the top and the impeller if you need to adjust it. You can either use easy to replace cartridges or often customize them with your own media.

Price And Reliability

The type of filter you choose for your 5 gallon aquarium can have a bearing on the price. Canisters are usually one of the most expensive filter types, although generally for larger tanks. HOBs tend to strike a good balance of great, customizable filtration at a reasonable price.

Whichever type you choose, you’ll want to make sure the product you buy is going to be reliable and will restart after a power outage, for example. The best way is to check reviews from current owners on sites like Amazon to establish this.

Our Verdict

5 gallon fish tanks are a great way of bringing aquatic life to your desk or small space. And while many have built-in filtration, there are plenty of excellent filters you can choose too.

We found the best 5 gallon aquarium filter to be the AquaClear 20 Fish Tank Filter. It’s really customizable with your choice of media, and as it’s compact and hangs off the back of your tank it will leave the maximum amount of room for your fish.

But there are many other alternatives on our list to help you find the best 5 gallon aquarium filter for your tank!

FAQs

Want to find the answers to the top frequently asked questions when it comes to choosing the best 5 gallon aquarium filter? Take a look below!

What Type Of Filter Is Best For A 5 Gallon Tank?

Our preference for the best 5 gallon aquarium filter is a hang on back style like the AquaClear 20 Fish Tank Filter, as it’s adjustable and easy to customize your media.

What Flow Rate Do I Need For A 5 Gallon Aquarium Filter?

A 5 gallon tank should have all its water completely cycled at least 4 to 5 times an hour. So look for a filter with a flow rate of 20 to 25 gallons per hour (GPH) as a minimum.

What If The Current Is Too Powerful?

The best 5 gallon aquarium filter should have an adjustable flow rate. But you can also use rocks or plants to buffer the outflow and create calmer areas in your tank.

How Often Should You Clean A 5 Gallon Filter?

Depending on your water parameters, HOBs, canisters, and internal filters may need cleaning every few weeks. But visually check your filter weekly and remove any gunk too.

Photo of author
AUTHOR
Matt Thomas
Matt has been keeping fish since junior high when he used to look after his parent's tank. He loves guppies, cichlids, and his crowntail betta named Bobby.

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