Choosing the Best Filter for a 40 Gallon Tank

At 40 gallons you are starting to get into the mid sized fish tanks. An aquarium of 40 gallons (180 litres) you are starting to get into the mid sized fish tanks. They are getting big enough for a much wider ranger of tropical freshwater fish species, including the larger Betta fish species, Mollies, Platies Danios etc. You will even have more room for plants and some aquascaping!

5 Best Filters for 40 Gallon Tanks

Here are our top picks for the best filter for 40-gallon tank:

Huijukon Air Pump Double Sponge Filter

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Great for 40 to 55 gallons, this sponge filter has a double sponge set up so it can be effective for most medium-sized tanks.

Its sponge has multiple layers so it can have more stages of cleaning while the duct has a right angle design so that the output air can’t easily blow away your fish.

There are 2 suction cups included in this package to make it easy to position in your tank.

It can be used for tanks that have betta fish, nano fish, goldfish, and even for babies and breeders.

You can also use it as a filter for non-fish such as shrimps and axolotl.

Things We Liked

Dual sponge system
Multiple layers of sponge material
Adjustable height
Great for gourami and betta fish
Both mechanical and biological filtration
Easy to clean

Things We Didn’t Like

Some air pumps may arrive slightly damaged

Penn Plax Undergravel Filter

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With a flat design that fits tanks of 40 to 55 gallons in size, this one measures 11.5 x 11.5 inches and has lift tubes on the sides, much like with every under gravel filter.

If you have a planted tank, this one can be a good choice since it doesn’t get in the way of your fish and plants.

The carbon filter cartridges on the side can remove foul odor from plants while it also doesn’t get in the way of beneficial bacteria in your aquarium.

It can be safe for use in both freshwater and saltwater tanks. If you don’t like extra maintenance or want a supplemental aquarium filter, this plate system might do the trick.

Things We Liked

Non-obtrusive
Good for planet tanks
Okay for freshwater and saltwater tanks
Has carbon filter cartridges
Great biological filtering

Things We Didn’t Like

Lacks power if used alone

Aquaneat Air Driven Bio Corner Filter Sponge

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As a sponge filter that is meant for corner placement, this one comes with its own set of accessories so you can easily set it up.

Measuring 4 x 3 inches, this one is adjustable in its telescoping height of 6 to 11 inches depending on how low or high your aquarium is designed.

With its suction cups, you can keep the corner filter from floating around. It also comes with 4 feet of airline tubing and other accessories.

With multiple layers, you can add your own filter media so you can customize this filter sponge in the way that you want it. Since it is meant for corners, you can also use it as a supplemental filter to your main one.

Things We Liked

Ideal for corners (not very obtrusive)
Comes with accessories
Telescoping adjustable height
Comes with airline tubing
Includes suction cups
Easy to install

Things We Didn’t Like

The instructions aren’t that clear

Water & Wood New Underwater Air Driven Corner Filter

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Yet another corner filter, this one has two-layer packs in one so you can place them in two spots in your tank.

You can use the filter pad at the top for mechanical filtration while the bio-sponge in the middle, as well as ceramic rings, can provide biochemical filtration.

Since it has multiple layers, you can also customize this filter to the way that you want the filter media to be laid down.

It also has noise reduction properties with the air pump. It also has a low bubble rate due to the air pump driving mechanism. It is also easy to disassemble for quick cleaning whenever needed.

Things We Liked

Easy to clean
Comes in a set of 2
Multiple layers of filtration
Customizable filter media trays
Okay for planted tanks

Things We Didn’t Like

Some filtration pads may require manual cutting to fit

Aquaneat Aquarium Bio Sponge Filter

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This bio sponge filter is a different version from the one we picked above – this one isn’t meant for corners but can be placed anywhere.

It is easy to set up with its own tools included while the size can accommodate from 40 to 60 gallons of tanks.

You can find it just right for fish that are small since it is not too powerful to suck up fish.

Examples of fish that may be okay with this filter are guppies, killifish, and the dwarf cichlid.

You can also use it for fry tanks and even breeders. It comes with its set of suction cups so it won’t easily go away when you put it on your tank.

Things We Liked

Compact design
Doesn’t suck up small fish
Okay for axolotl tanks
Good for breeding tanks
Easy to find replacement sponges

Things We Didn’t Like

The instructions aren’t clear enough

Things to Consider

In choosing the best filter for a 40-gallon tank, here are some criteria:

Why should I buy a filter for a fish tank?

A filter for a fish tank is important so that you don’t change your tank water too often. Doing so can make it less annoying for your fish, especially those that require marine conditions such as saltwater fish.

If your fish tank is maintained by a filter then you don’t have to do the chore of having to change the water too often.

What’s more, many filters also have biological filters, which depend on beneficial bacteria that grow and eat up algae. This means less likelihood of algae clogging up your tank!

How do I choose the best tank filter for 40 gallons?

Type of filter. The best type for 40 gallons is a sponge filter since it is not too costly and does the job fine for a medium-sized tank. The sponge filter is beneficial for its mechanical and biological filtration, provided that you don’t wash the sponge too often to maintain the beneficial bacteria.

Other types of filters for other sizes could be:

Hang-on back filter – best for medium to large tanks.
Canister filter – best for large tanks and large fish.
Undergravel filter – ideal for small to medium tanks, as well as planted tanks.
Internal filter – great for most medium to large tanks.

Type of filter media. Nearly any type of filter media can work just fine on a small to the medium-sized tank. The best type for 40 gallons would be any of the following:

Ceramic rings
Bio-balls
Activated carbon

You can buy most of these filter media from the store. However, not all filter media will fit on your chosen filter, so consider looking up the filter media tray’s size and dimensions so that you know what to buy in the store!

There are also certain brands of filters, such as Penn Plax and Marineland that sell their own brand of filter cartridges, so you can just go ahead and buy those if they are specifically sized for your filter tray. This can save you a lot of time in trying to cut them.

What are the different kinds of tank filters?

The different kinds of tank filters are the following:

Type of filter	Best for	Not So Good for
Under gravel	Saving space Biological filtration Looks classic Planted tanks	Removing nitrates Sludge problems Chemical filtration Mechanical filtration
Sponge filters	Easy to cleanInexpensiveCan be used on different aquarium sizes	May require a powerful air pump
HOB or Hang-on Back	Inexpensive Easy to use Mechanical and chemical filtration	Biofiltration
Canister Filters	Large tanks More power Marine aquariums	Your budget – Expensive Tidyness – can be messy / water spills Time-consuming

Conclusion

Our top pick for the best filter for 40-gallon tank is the Huijukon Air Pump Double Sponge Filter because of its dual sponge system, the multiple layers of sponge material, and its adjustable height. It can also work great for gourami and betta fish and features both mechanical and biological filtration.

Overall, we think that it is simple and easy to clean and maintain