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No matter what size aquarium you own, a fish tank filter is a basic necessity to keep your water clean and your fish healthy. A tank without a filter or an aquarium filter not working will result in dirty water, which can severely impact the health and happiness of your fish.
To help you on your search for a suitable 40 gallon fish tank filter, I’ve reviewed a variety of products and analysed their positives and negatives.
After considering all the options our top picks were…
Review Summary
Penn Plax Aquarium Cascade 700 Canister Filter
With a water flow rate of 185 GPH, the Penn Plax 700 canister filter is a good option for any 40-gallon tank. It comes with two large filter media baskets that are already packed with media for convenience, as well as all the necessary parts you’d expect with an external canister filter.
Best All-Rounder: Penn Plax Aquarium Cascade 700 Canister Filter
For the majority of 40-gallon aquariums, this filter is my overall recommendation.
This canister filter from Penn Plax is a good choice for most 40-gallon tanks. It has 3-stage filtration, a water flow rate of 185 GPH (that can also be adjusted), and two large media baskets. It operates relatively quietly, which is a plus!
MarineLand Magnum Polishing Internal Canister Filter
The MarineLand internal canister filter is extremely powerful, capable of filtering 290 gallons per hour. This is more than enough for a 40-gallon tank.
Best on a Budget: MarineLand Magnum Polishing Internal Canister Filter
This filter is good-quality and extremely affordable.
MarineLand’s internal canister filter can clean up to 270 gallons per hour, making it an ideal choice for your 40-gallon tank. It’s a low-cost option with 3-stage filtration, and also comes with a micron cartridge to keep your aquarium sparkling clean.
Fluval are known for making top-quality filters, and this one is no exception. It’s suitable for tanks up to 45 gallons and has a water flow rate of 206 GPH
Editor’s Choice: Fluval 207 External Filter
My personal favorite filter. It’s very high-quality but pricey as a result.
The Fluval 207 canister filter is costly but offers high-quality 3-stage filtration for your tank. It features an adjustable water flow rate, multiple filter media baskets, and operates quietly. It can filter 206 gallons per hour.
Types of Filters
To help you find the ideal 40 gallon fish tank filter, let’s first get to know the different types of filters. There are a huge amount of aquarium filters on the market, which can seem a little overwhelming. They all have the same purpose, which is to clean your tank water, but certain types are better suited to different setups and species of fish.
Undergravel Filters
An undergravel filter is positioned under your substrate to suck up water via uplift tubes. They are generally paired with an airstone and air pump or powerhead.
TIP
Using an undergravel filter does mean you have to thoroughly clean your substrate often due to build-up of detritus and hydrogen sulfide.
Wet/Dry Filters
Wet/dry filters are typically used in saltwater aquariums. They work by pumping water from your tank through a drip plate or a rotating arm.
The water is then pushed through biological material inside the filter chamber before being deposited back into your tank (either directly or via a sump). This type of filter is best for tanks with high levels of oxygen for optimal performance.
Canister Filters
Canister filters are popularly used by aquarists in tanks over 40 gallons. They can be a bit pricey but are an excellent investment for large aquariums.
A canister filter pulls water up through a lift tube, which is then pushed into an external filter chamber via a pump. Once inside the chamber, the water is pressed through filter media before it makes its way back into the aquarium through another tube.
Internal Filters
An internal filter is a good option for tanks that are under 20 gallons. They are placed directly into the tank and suck water up through the bottom of the filter. The water then pushes through a sponge that catches debris and waste. The sponge contains beneficial bacteria that convert ammonia into nitrite and nitrite into nitrate.
A lot of internal filters require an airline that is attached to the filter inlet. Air is pumped through the bottom of the filter via an air pump. Air bubbles dissipate at the water surface, creating water movement that allows the filter to perform.
Hang On Back/Power Filters
A hang on back/power filter is put onto the back of your tank. A siphon tube draws up water and pushes it through filter media.
Air-Driven/Sponge Filters
Air-driven/sponge filters are best used in breeding, hospital, nursery, and invertebrate/small fish tanks. They offer biological and mechanical filtration.
This type of filter works with an air pump, power head, or another type of filter, where water is pulled up through a sponge. Find out more about saltwater powerheads here.
Watch the video below to see how the different kinds of filters looks.
Which Type of Filter is Best for a 40-gallon?
I recommend using a canister filter for a 40-gallon tank, especially in planted and saltwater aquariums. They provide excellent chemical, mechanical, and biological filtration, and work exceptionally well in large setups with heavy bio-loads.
TIP
However, canister filters can be fairly costly, so if you’re on a budget, then an internal or power filter is also an adequate option.
3 Way Filtering Function
Chemical Filtration
Chemical filtration removes particulates from your aquarium using activated carbon, resin, or another type of absorbent. It’s especially helpful for getting rid of unpleasant odors and medication.
Mechanical Filtration
Mechanical filtration removes particles like excess food, dirt, and fish waste from your tank. It’s most effective when paired with biological filtration.
Biological Filtration
Biological filtration is the process of beneficial bacteria converting harmful toxins into much less dangerous forms. This is why all tanks need to be cycled before being stocked with fish.
Which is Best for a 40-gallon Tank?
I recommend using all three types of filtration in your 40-gallon tank. Chemical filtration is optional, but biological and mechanical filtration are vital.
Water Flow Rate
Your aquarium filter needs to have an appropriate water flow for your tank capacity in order to perform its job properly.
RECOMMENDATION
As a minimum, your filter should be able to clean at least four times the size of your aquarium per hour.
For example, a filter for a 40-gallon tank should have a water flow rate of at least 180 GPH (gallons per hour). Reef tanks and setups with large species of fish will require a higher water flow rate.
Maintenance and Filter Media Replacement
Regular maintenance of your aquarium filter is important for making sure it performs to its full potential. You should frequently check your filter for signs of damage and dirt.
TIP
It’s a good idea to clean your filter around every four weeks. This involves taking it apart and wiping away any gunk that might have built-up.
Filter media loses its effectiveness over time but most types do not need to be replaced too often. Media like ceramic rings and coarse foams only need changing when they are falling apart, or have developed larger pores.
In contrast, activated carbon needs to be replaced every two to four weeks as it loses its maximum absorbency fairly quickly. Filter floss also needs changing around every 5 days or when it is dirty. When cleaning your filter or filter media, only use water from your tank and avoid tap water.
NOTE
Additionally, it’s crucial you seed your new biological filter media for at least two weeks (ideally, longer!) before discarding your old one. Your bio-media houses a large portion of beneficial bacteria that are important for your tank’s ecosystem.
Throwing away your old filter media without seeding your new one first can have disastrous consequences.
40-gallon Fish Tank Filters Reviews
Penn Plax Aquarium Cascade 700 Canister Filter
With a water flow rate of 185 GPH, the Penn Plax 700 canister filter is a good option for any 40-gallon tank. It comes with two large filter media baskets that are already packed with media for convenience, as well as all the necessary parts you’d expect with an external canister filter.
Best All-Rounder: Penn Plax Aquarium Cascade 700 Canister Filter
With a water flow rate of 185 GPH, the Penn Plax 700 canister filter is a good option for any 40-gallon tank. This filter is my overall recommendation as it’s not too expensive and offers adequate 3-stage filtration.
It comes with two large filter media baskets that are already packed with media for convenience..
It comes with two large filter media baskets that are already packed with media for convenience, as well as all the necessary parts you’d expect with an external canister filter. Unfortunately, the baskets don’t fit together as well as they should.
This filter isn’t too difficult to install and clean but can be a little time-consuming. It has a push-button to make setup a bit simpler, as well as swimming-pool-style hose clamps that can be easily lifted for cleaning and basic maintenance. The water flow rate can also be adjusted.
TIP
Removing the tubes for maintenance can be a bit frustrating as they can leak a hefty amount of water. To counteract this, consider keeping the filter in a bucket.
My favorite feature about this filter is it functions fairly quietly. Although not entirely silent, the filter doesn’t emit a high level of noise.
A downside with the Penn Plax Cascade 700 filter is that the media it comes with is not the best quality, so it might be a good idea to purchase separate filter media.
Specs
- Filter Type: Canister
- Size: 11.5” x 15” x 10”
- Weight: 10 lbs
- Recommended Tank Size: Up to 65 gallons
Pros
- 3-stage filtration
- Operates fairly quietly
- Large filter media baskets
- Adjustable water flow rate
Cons
- Can be time-consuming to setup and clean
- Can leak when tubes are removed
- Included filter media isn’t the best quality
MarineLand Magnum Polishing Internal Canister Filter
The MarineLand internal canister filter is extremely powerful, capable of filtering 290 gallons per hour. This is more than enough for a 40-gallon tank.
Best on a Budget: MarineLand Magnum Polishing Internal Canister Filter
The MarineLand internal canister filter is extremely powerful, capable of filtering 290 gallons per hour. This is more than enough for a 40-gallon tank.
The MarineLand internal canister filter is extremely powerful, capable of filtering 290 gallons per hour…
It offers great chemical, mechanical, and biological filtration. The floss sleeve catches dirt and debris, while the activated carbon removes bad smells and other water impurities.
In operation, the filter does not produce a huge amount of noise, but it can emit a slight buzzing or humming sound at times.
The design of the filter features a dual-chamber, which gives a lot of space for beneficial bacteria to grow in. It also means you can add extra filter media, such as when you’re setting up a new tank and want to jumpstart the cycling process!
To polish your tank water further, the MarineLand internal canister filter comes with a reusable pleated micron cartridge.
To polish your tank water further, the MarineLand internal canister filter comes with a reusable pleated micron cartridge. You can charge it with diatomaceous earth to make it even more effective.
Setting up the filter does involve a bit of mental gymnastics, unfortunately. There are a lot of parts, including some that could easily go missing due to how small they are. Cleaning this filter is also a bit of a hassle for this reason.
Additionally, the filter is quite bulky and large, so it is quite noticeable when placed in your aquarium. If you have a lot of plants or rocks/décor, then you could arrange them around the filter to make it less visible.
Specs
- Filter Type: Internal canister
- Size: 8.5” x 5.8” x 11”
- Weight: 3 lbs
- Recommended Tank Size: Up to 97 gallons
Pros
- Capable of filtering 290 GPH
- 3-stage filtration
- Features a large dual-chamber
- Comes with a reusable micro cartridge
Cons
- Large, bulky design
- Difficult to install and clean
- Can be a bit noisy
Fluval are known for making top-quality filters, and this one is no exception. It’s suitable for tanks up to 45 gallons and has a water flow rate of 206 GPH
Editor’s Choice: Fluval 207 External Filter
Out of all the products I’ve reviewed, the Fluval 207 canister filter is by far my favorite. Fluval are known for making the best canister filters, and this one is no exception. This filter is an updated version of the Fluval 206 filter.
It can hold an impressive amount of filter media and allows for better direct contact to your filter media due to its unique shape…
It’s suitable for tanks up to 45 gallons and has a water flow rate of 206 GPH. It can hold an impressive amount of filter media and allows for better direct contact to your filter media due to its unique shape. This makes sure your tank is getting the best filtration possible.
In operation, the filter is mostly silent. If your aquarium is located in your bedroom, then this filter is an excellent option.
The filter features a clog-proof intake strainer, patented Aqua-Stop valve, numerous filtration baskets…
The filter features a clog-proof intake strainer, patented Aqua-Stop valve, numerous filtration baskets (each stocked with chemical, mechanical, and biological filter media), and rim connect assemblies to make sure the intake and output hoses stay firmly in place. This filter is self-priming and lets you adjust the water flow rate, too.
Installation and Maintenance
Cleaning and installing the Fluval 207 filter isn’t too complicated, but it can be a bit challenging the first few times. Disconnecting the tubes can cause a bit of water to flow out, and the filter is prone to leaking in general.
It might be wise to keep the filter in a bucket, especially during maintenance.
Although this filter is a bit more expensive than the other ones I’ve reviewed, I think it is a worthwhile investment.
Specs
- Filter Type: Canister
- Size: 7.5” x 7” x 16.5”
- Weight: 6.4 lbs (with packaging)
- Recommended Tank Size: Up to 40 gallons Full Specs
Pros
- Large media baskets
- Operates fairly quietly
- Adjustable water flow rate
Cons
- Can be difficult to install and clean
- Prone to leaking
Aqua-Tech Power Aquarium Filter
It’s suitable for aquariums between 30 and 60 gallons, so should have no problem providing your tank with good filtration. It features 3-stage filtration and comes with filter cartridges for convenience
Aqua-Tech Power Aquarium Filter
If a canister filter doesn’t seem like the best match for your tank, then the Aqua-Tech power filter is a great option. It’s suitable for aquariums between 30 and 60 gallons, so it should have no problem providing your tank with good filtration.
If a canister filter doesn’t seem like the best match for your tank, then the Aqua-Tech power filter is a great option…
It features 3-stage filtration and comes with filter cartridges for convenience, which contain activated carbon for eliminating odors and water impurities.
Installation
Canister filters can be a bit tricky and frustrating to setup, so a power filter is an excellent alternative as they are very simple to install. Cleaning is also a breeze, so you don’t need to worry about external chambers or tubes leaking during maintenance like with a canister filter.
What I really like about the Aqua-Tech power filter is how quiet it is. It makes hardly any sound, which is ideal if your aquarium is located in your bedroom.
However, this filter can lose its suction over time and get clogged up quickly. If you have a 40-gallon tank with a heavy bioload, then this could be problematic. I have a bristlenose pleco in my 40-gallon who produces a lot waste, so this filter could struggle cleaning tanks with big bio-loads like mine.
Specs
- Filter Type: Power
- Size: 6.2” x 14.3” x 7.8”
- Weight: 2.78lbs
- Recommended Tank Size: 30 to 60 gallons
Pros
- 3-stage filtration
- Operates quietly
- Simple to install and clean
Cons
- Clogs up and loses suction easily
- Might struggle cleaning tanks with heavy bio-loads
Polar Aurora External Aquarium Filter
This canister filter from Polar Aurora provides 3-stage filtration and has a water flow rate of 264 GPH, so is more than powerful enough for a 40-gallon tank. It’s also affordable and doesn’t create a lot of noise.
Polar Aurora External Aquarium Filter
This canister filter from Polar Aurora provides 3-stage filtration and has a water flow rate of 264 GPH, so is more than powerful enough for a 40-gallon tank. It’s also affordable and doesn’t create a lot of noise.
This canister filter from Polar Aurora provides 3-stage filtration and has a water flow rate of 264 GPH, so is more than powerful enough for a 40-gallon tank…
The filter includes three media trays and an adjustable spray bar. The latter is a useful feature as it allows you alter the output flow from the filter.
Installation and Maintenance
Cleaning and setup aren’t too challenging, but might be a bit fiddly initially. If you’re unfamiliar with canister filters or haven’t used one before, then it might be worthwhile looking up maintenance instructions or videos.
Two of my main gripes with the Polar Aurora filter are its durability and design. I’m not a huge fan of its appearance, as it looks very bulky. As this filter isn’t too expensive, the quality of it is not as great as more pricey filters, which can cause it to breakdown prematurely.
Specs
- Filter Type: Canister
- Size: 10” x 10” x 16”
- Weight: Unknown
- Recommended Tank Size: Up to 75 gallons
Pros
- Adjustable water flow rate
- Three media trays
- Operates fairly quietly
Cons
- Can be a bit fiddly to setup and clean
- Design flaws
Conclusion
After considering all the options our top picks were…
Best All-Rounder
For most 40-gallon aquariums, I think the most suitable filter is the Penn Plax Aquarium Cascade 700 Canister Filter. It’s fairly inexpensive but provides 3-stage filtration and a water flow rate of 185 GPH.
I like that the filter operates quietly and comes with two large media baskets. Both of these are features I really appreciate in a filter.
A couple of negatives, however, are its design and time-consuming maintenance. Although the appearance of the filter is appealing, some parts do not fit together as well as they should.
Maintenance
Installing and cleaning the filter isn’t overly difficult, but it can be time-consuming. Additionally, disconnecting the tubes during maintenance can result in water gushing out, even when switched off.
This isn’t a huge issue as you can keep the filter in a bucket to prevent any leaks.
My other top recommendations are the MarineLand Magnum Polishing Internal Canister Filter and Fluval 207 External Filter. These two filters are on opposite scales of the spectrum, as the former is the least expensive and the latter is the most expensive.
Best on a Budget
MarineLand’s internal canister filter is a good option if you’re on a budget, featuring a water flow rate of 290 GPH and large dual-chamber. Unfortunately, it does produce a bit of noise and can be a hassle to clean.
Editor’s Choice
My personal favorite is the canister filter by Fluval. It’s high-quality, operates quietly for the most part, and has a water flow rate of 206 GPH. It also comes with large filter media baskets. The downsides with this filter are its difficulty to clean and tendency to leak.
If these three filters don’t appeal to you, then the other two filters on this list are still great choices and might be worth considering instead.
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Thanks for reading! Hope you found the ideal 40 gallon fish tank filter. If you found this article helpful, feel free to share it!
