Best Aquarium Internal Filters (Reviewed 2021)

Updated on January 7, 2021 by

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How efficient is an aquarium internal filter?

It is no doubt that without the best aquarium filters and their media, the aquatic creatures would be at high risk, living in a poor environment which could even lead to their death eventually.

However, the best filter media cannot function on their own without being hosted by a system otherwise called filters, through which they can be able to affect the aquarium water and create an environment that is safe and healthy for all aquarium inhabitants.

If you’re on the lookout for more powerful filtration options, have a look at our best canister filters, or best HOB filters articles.

In other words, a filter is a chamber that houses the filter media and regulates the filtration of the water that passes through it in order to create a habitable aquarium.

They are used to house bio-media that have enough nook and crannies which provide a home space that facilitates the colonization, growth, and activity of beneficial bacteria that are useful in converting the toxic waste to a lesser harmful material.

They are also useful in controlling the nitrogen cycle including ammonia, nitrate, and nitrite level in the water.

A filter is also used to oxygenate the water and regulate the water flow in the tank. Therefore it is recommended to employ one that has a water flow of about 4 times or even more than the actual tank capacity itself. This water flow is regarded as the gallon per hour (GPH) and is strictly related to the tank.

Some filters are internal, usually sitting inside the tank, and are often recommended for smaller tanks, while some filters are external, usually bulky, and might not be able to sit inside the tank, which makes them more suitable for larger tanks.

Usually, most filters will follow a similar procedure, in which a motor draws water into the filter, by the activity of the filter media the water is filtered, thereby delivering cleaner and healthier water back to the tank.

However, depending on their different mode of operation system, the best aquarium filters can be grouped into 5 different types, namely:

  1. Canister Filters
  2. Sponge Filters
  3. HOB Filters (Power Filter)
  4. Undergravel Filters
  5. Sump Filters

Best aquarium internal filters in 2020 compared

ImageProductRatingPrice
Best Overall Filter
Fluval U4 Underwater Filter
Fluval U4 Underwater Filter

For Tanks: Up to 65 Gallons
Flow Rate: 190 GPH adjustable
Includes: Spray bar
Models: 3 smaller available

9.9
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Great Internal Filter
Aqueon Quietflow Internal Filter
Aqueon Quietflow Internal Filter

For Tanks: Up to 40 Gallons
Flow Rate: 155 GPH adjustable
Adjustable: Return height & direction

9.5
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Best Nano Filter
Aqueon QuietFlow Internal E 3
Aqueon QuietFlow Internal E 3

For Tanks: Up to 3 Gallons
Other Models: for 10-20-40 Gallons
Flow Rate: 25 GPH

9.1
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Fresh & Saltwater
Penn-Plax Cascade 600 Filter
Penn-Plax Cascade 600 Filter

For Tanks: Up to 50 Gallons
Flow Rate: 175 GPH adjustable
Adjustable: Pump head direction
Outake: Pump head or Spray bar

9.4
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Quiet Nano Filter
Penn-Plax Cascade 300 Filter
Penn-Plax Cascade 300 Filter

For Tanks: Up to 10 Gallons
Flow Rate: 70 GPH adjustable
Adjustable: Pump head direction
Outake: Pump head or Spray bar

9.3
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A Great Price Deal
Penn-Plax Cascade 170 Filter
Penn-Plax Cascade 170 Filter

For Tanks: Up to 10 Gallons
Flow Rate: 45 GPH adjustable
Adjustable: Pump head direction
Outake: Pump head or Spray bar

9.1
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Best for Large Tanks
MarineLand Internal Filter
MarineLand Internal Filter

For Tanks: Up to 97 Gallons
Flow Rate: 290 GPH
Outake: Pump head

9
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Effective Filter
Tetra Whisper Internal Filter
Tetra Whisper Internal Filter

For Tanks: Up to 40 Gallons
Flow Rate: 170 GPH
Outake: Pump head

8.8
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UV Sterilizer Filter
COODIA Internal Filter
COODIA Internal Filter

For Tanks: Up to 75 Gallons
Flow Rate: N/A
Includes: Air bubble, UV light

Outake: Pump head

8.7
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Most Silent Filter
Sicce Shark Internal Filter
Sicce Shark Internal Filter

For Tanks: Up to 53 Gallons
Flow Rate: 211 GPH
Intake: Adjustable diameter

8.5
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Best Filter for Betta
Fluval Nano Aquarium Filter
Fluval Nano Aquarium Filter

For Tanks: Up to 15 Gallons
Flow Rate: 45 GPH
Outake: Spray bar

8.4
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1. Fluval U4 Underwater Filter – Best Overall Aquarium Internal Filter

Up to 65 Gallons Tanks
Fluval U4 Underwater Filter - Best Overall Aquarium Internal Filter

Fluval U4 Underwater Filter

This is a Fluval product that offers improved underground filtration suitable for freshwater and saltwater aquarium tanks. It can be installed vertically or horizontally to suit your aquatic lifestyle.

It has a high-quality filtration mechanism that facilitates optimal mechanical and biological filtration.

It is designed with an economical power output and adaptable fluctuating voltage and frequency for efficient performance.

It includes a 3-way flow control system with adjustable output. It also has an integrated spray bar that allows for a gentle and even distribution of water flow for the aquarium plants.

It also comes with 2 foam pads, 2 poly/carbon cartridges and 40 grams biomax, making it suitable for fresh or saltwater tanks up to 65 gallons.

PROs
  • 3-way flow control system with adjustable output
  • Silent and effective operation
  • Suitable for freshwater and saltwater environments
  • Ideal for a supplemental or standalone filter
  • Improved mechanical and biological filtration
CONs
  • Top knob may come off easily

2. Aqueon Quietflow – Powerful & Quiet Aquarium Internal Filter

Up to 40 Gallons
Aqueon Quietflow Internal Power Filter - Powerful & Quiet Aquarium Internal Filter

Aqueon Quietflow Internal Power Filter

Aqueon Quietflow Internal Power Filter is one of the best cheap internal filters that is suitable for both aquarium and terrarium use.

They are excellent at controlling the water flow in many ways, including adjusting the flow rates, flow directions and the flow height.

Aqueon filters offer a three-stage filtration which includes: a dense foam for entrapping particles and debris, an activated carbon that controls dissolved toxins, odors, and discoloration, and a patented bio grid that supports beneficial bacteria growth which is necessary for reducing ammonia and nitrate level.

They have a simple installation setup with the aid of a directional return pipe which allows for vertical or horizontal mounting.

Each unit of this internal filter is preloaded with an Aqueon replaceable cartridge(s).
Very quiet, small and comes with quite an affordable price tag, which makes it suitable for a low budget plan.

However, they are not suitable for tanks with small shrimp, as they will often get sucked in, and might result in loss of the species.

PROs
  • Simple installation setup
  • Preloaded with replaceable cartridge(s)
  • 3-stage filtration system
  • 3-way water flow control
  • Fairly cheap
CONs
  • Unsuitable for small shrimp tanks

3. Aqueon Quietflow E – Best Internal Filter for Turtle Tanks

Up to 3 Gallons
Aqueon QuietFlow E Internal Filter - Best Internal Filter for Turtle Tanks

Aqueon QuietFlow E Internal Filter

This is a great economical filter with improved quality and easy to use.

It is self-priming as it has an auto-start pump which requires no priming and will automatically restart after a power fluctuation.

They can be easily installed with the aid of a suction cup and/or hanging clips.

They are built with a carbon cartridge that facilitates chemical filtration by removing toxins, odor, and discoloration from the water. It is recommended to change their filter cartridge every 4 weeks to avoid the buildup of wastes that could flow back into the water.

The Quietflow 10, 20 and 40 units will always facilitate biological and mechanical filtration systems.

However, this device might get a bit noisy when the impeller is moved. This will call for immediate adjustment.

PROs
  • It is self-priming
  • Comes with a built-in carbon cartridge
  • Easy to install and maintain
  • Effective water filtration
  • Fairly cheap
CONs
  • Might get noisy when the impeller is moved

4. Penn-Plax Cascade 600 – Fresh & Saltwater Aquarium Internal Filter

Up to 50 Gallons
Penn-Plax Cascade 600 Submersible Filter - Fresh & Saltwater Aquarium Internal Filter

Penn-Plax Cascade 600 Submersible Filter

The Penn-Plax Cascade 600 Submersible Aquarium Filter is a fully submersible aquarium filter suitable for freshwater and saltwater aquarium tanks.

They are recommended for a 20-50 gallon tank and offer up to 175 GPH of sparkling clean water.

It can be easily installed with the aid of the included suction cup and can be placed in a horizontal direction.

The filters are specially designed with a built-in carbon that facilitates chemical filtration by removing toxic chemicals, odors, discoloration and other chemical contaminants from the tank.

Moreover, are also designed with an internal sponge that encourages the buildup of beneficial aerobic bacteria necessary for biological filtration. The Penn Plax Cascade 600 Submersible Aquarium Filter comes with a pump head that has an adjustable and directional water flow.

They also have a spray bar option which allows you to distribute water evenly and helps to aerate the water.

PROs
  • Fully submersible
  • Included suction cup
  • Built-in carbon cartridge
  • Comes with a spray bar as well
CONs
  • Quite noisy

5. Penn-Plax Cascade 300 – Best Internal Filter for Nano Tanks

Up to 10 Gallons
Penn-Plax Cascade 300 Submersible Filter - Best Internal Filter for Nano Tanks

Penn-Plax Cascade 300 Submersible Filter

This is another great Penn-Plax product that offers you another choice to suit your aquatic setup.

Just with every other Penn-Plax product, this filter is fully submersible and is suitable for freshwater and saltwater aquariums.

The Penn-Plax Cascade 300 Submersible Aquarium Filter measures 5’ long by 2’ wide by 3’ deep and is recommended for nano and small tank size usually within the range of 1.5-10 gallons and produces up to 70 GPH of well-filtered water.

It also comes with an activated carbon cartridge that facilitates chemical filtration by detoxifying harmful toxins and removing odors, discoloration and other dissolved contaminants from the water. 

It is also built with an internal sponge that encourages the optimal growth and activity of beneficial aerobic bacteria that allows for biological filtration.

It comes with a pump head that allows for adjustable and directional water flow while it also aerates the water.

The spray bar option helps to distribute water evenly in the tank.

PROs
  • Fully submersible
  • Included suction cup
  • Built-in carbon cartridge
  • Comes with a spray bar included
CONs
  • Suitable only for nano and small tanks

6. Penn-Plax Cascade 170 – Best Cheap Aquarium Internal Filter

Up to 10 Gallons
Penn-Plax Cascade 170 Submersible Aquarium Filter - Best Cheap Aquarium Internal Filter

Penn-Plax Cascade 170 Submersible Aquarium Filter

This is yet another Penn-Plax product with superior quality that comes with a fair price tag that suits your budget plan.

Penn-Plax (CIF4) Cascade 170 Submersible Aquarium is a fully submersible filter suitable for a small aquarium setup that provides enhanced filtration and aeration above and below the surface. 

They are built with high-quality components that facilitate an improved filtration including Cascade Filter, Air Muffler, Flow Nozzle, Suction Cups, Air Tube, and Bio-Sponge.

The Cascade internal filter provides a 3-way improved filtration (physical, biological and chemical filtration) while aerating the water.

It has an adjustable and directional pump head that delivers 45 GPH of clean filtered water.

It also has a spray bar option which enables an even water distribution.

PROs
  • Activated carbon cartridge for optimized chemical filtration
  • Internal bio-sponge for optimized colonization of useful bacteria
  • Adjustable and directional water flow
  • Suitable for freshwater and saltwater
  • Spray bar option
CONs
  • Might get noisy

7. Marineland Magnum – Best Aquarium Internal Filter for Large Tanks

Up to 100 Gallons Tanks
MarineLand Magnum Internal Canister Filter - Best Aquarium Internal Filter for Large Tanks

MarineLand Magnum Internal Canister Filter

The Marineland Magnum Polishing Internal Canister Filter is a great internal filter that uses two refillable chambers that provides room for carbon or other customizable filter media.

This filter provides 290 GPH filtration that is suitable for small and larger tanks up to 97 gallons.

It offers a 3-way filtration process including physical, biological, and chemical filtration.

It has a micron cartridge that facilitates a high quality polished and sparkling filtered water.

It is built with a quick and easy to start submerged motor which does not necessarily require priming.

This device may easily get clogged, which requires frequent cleaning and maintenance. The filter should be cleaned every 2-4 weeks while the micron cartridge should be cleaned every month.

However, this device may often produce some sporadic buzzing sound that may be uncomfortable.

PROs
  • Offers a 3 stage filtration
  • Included micron cartridge to facilitate water polishing
  • Submerged motor for easy startup
  • No necessary priming
CONs
  • Frequent cleaning and maintenance
  • Often sporadic buzzing noise

8. Tetra Whisper – Best Effective Aquarium Internal Filter

Up to 40 Gallons
Tetra Whisper In-Tank Filter with BioScrubber - Best Effective Aquarium Internal Filter

Tetra Whisper In-Tank Filter with BioScrubber

Tetra Whisper In-Tank is designed with a complete air pump and water filter system that is suitable for freshwater and saltwater aquariums up to 40 gallon tanks.

The air pump delivers up to 170 GPH while aerating the water.

It comes with an internal filter that can be mounted inside the aquarium with the aid of an included clip. This enables placing the tank flush against the wall.

Each filter has an included one large easy to change and pre-assembled whisper bio-bag filter cartridge.

It consists of a dense dual-sided mesh that facilitates an effective filtration, removing debris and fish waste.

With the aid of a suction cup and/or bracket mounting, this device can adapt to varying water levels ranging from high to low.

PROs
  • Effective filtration
  • Suitable for freshwater and saltwater tanks
  • Comes with a pre-assembled whisper bio-bag filter cartridge
  • Has a dense dual-sided mesh for effective filtration
CONs
  • Gets noisy in a low water tank
  • Very fragile

9. COODIA UV Internal Filter – Best Internal Filter with UV Sterilizer

Best for Saltwater
COODIA Internal Green Water Killer Filter

COODIA Internal Green Water Killer Filter

This is a great filter that is suitable for freshwater and saltwater aquarium tank and delivers an effective filtration up to a 150-gallon tank.

A strong suction cup is included to facilitate easy installation of the filter in the tank.

It is built with an anticorrosive ceramic rotator sterilizer that is suitable for saltwater and freshwater tank.

It comes with a 5 watt adjustable water pump that allows for effective water flow while oxygenating the water. This water pump also has an adjustable outlet to adjust the direction of the water flow.

Moreover, It also has an air bubble that helps to generate bubbles to the water.

It has an included 5 watt UV light that enables a lighted tank for a clear view at night and suitable for most aquatic species.

PROs
  • Included 5 watt UV light
  • 5-watt adjustable water pump
  • Anticorrosive ceramic rotator sterilizer
  • Suitable for saltwater and freshwater
  • A strong suction cup for easy installation
CONs
  • Quite pricey
  • UV is hardly seen during the day

10. Sicce Shark ADV 800 – Most Quiet Aquarium Internal Filter

200+ GPH Flow Rate
Sicce Shark ADV 800 Internal Aquarium Filter

Sicce Shark ADV 800 Internal Aquarium Filter

The Sicce Shark 800 Internal Aquarium Filter is a high-quality filter that delivers a flow rate of up to 211 GPH, being suitable for freshwater and saltwater tanks up to 53 gallons.

It comes with an additional compartment that allows for an extra filter to improve the filtration capacity in the tank.

It employs the venture system to facilitate oxygenated water which is evenly distributed throughout the tank.

This device is designed with a transparent body which makes it easy and clear to see the debris and dirt build-up, therefore reducing the rate of unseen clogging in the filter.

It comes with an adjustable intake diameter to ensure that the aquatic species are not sucked up into the filter. This is a safety measure for your aquatic species.

It has a magnetic connection that enables a tightly sealed grip around the hose openings. This setup also ensures optimized water flow regulation.

PROs
  • Additional filtration compartment for improved filtration
  • Transparent body for an easy and clear view
  • Venture system to facilitate water oxygenation
  • Adjustable inlet diameter
  • Magnetic connection for tight grips
CONs
  • Relatively expensive

11. Fluval Nano – Easiest to Maintain Aquarium Internal Filter

Best for Betta Tank
Fluval Nano Aquarium Filter - Easiest to Maintain Aquarium Internal Filter

Fluval Nano Aquarium Filter

This is a great filter especially suitable for planted nano tanks.

It comes with an improved filter media that facilitates a 2-way filtration including mechanical and biological filtration.

It facilitates quality oxygenated water that is beneficial to the aquatic organisms, with an adjustable output flow rate that has an attachable spray bar that evenly distributes a gentle water flow which makes it safe even for delicate species.

This filter can be easily assembled and disassembled which makes it easier to install, clean and maintain.

It also comes with 3 suction cups for easy installation that enables it to be securely fixed in the tank.

PROs
  • Improved water oxygenation
  • Adjustable output flow rate
  • Easy installation and maintenance
  • 3 suction cups included
  • Attachable spray bar for even distribution
CONs
  • The spray bar is fragile and can easily break

What filter type is suitable for my aquarium?

These are varieties of filter forms to suit your style; nonetheless they have their different advantages and disadvantages over each other. 

Canister filters are more suitable for larger tanks above 40 gallons and can house the three different filter media (Mechanical, Biological, and Chemical). They are very efficient compared to other filters but come with an expensive price tag and a little bit more difficulty in setup and maintenance.

Sponge filters are not very suitable as a standalone filter, but more of an additional filtration system to other existing filters. However, they are very simple to set up and come as a sponge shaped cylinder that is fully immersed into water with a great longevity. Also, they require an air pump with or without an air stone for filtration.

HOB filters (power filters) are most suitable for small nano tanks. They also facilitate three types of filtration, while coming with a cheap price tag. They are quite easy to set up, maintain, and change the filter media. However, when the media are replaced, they lose all their beneficial bacteria.

Undergravel filters have a large surface area that is beneficial for the growth of nitrifying bacteria. They also have a simple and straightforward setup and maintenance. However, they require regular maintenance and often slow down plant growth by oxidizing the plant nutrients.

Without a full sump setup, the sump filter is rather a container to house the filter and other equipment such as the skimmers and heaters. The sump filter is usually employed to impede the water overflow. They are quite affordable and have a simple setup. They are also suitable for larger tanks.

But most importantly, some filter types could be great for an aquarium and unsuitable for another. Therefore, when choosing the best internal filter type, the following criteria should be considered to suit your aquatic setup:

  1. Aquarium type
  2. Aquarium volume
  3. Fish and plant species
  4. Gravity
  5. Flow rate
  6. Cost

To conclude

Aquarium filters are one of the most important aquarium accessories that will ensure that your aquatic species live and thrive in a safe, healthy, and comfortable environment.

This ensures that quality water conditions would be maintained at all times.

Some filter systems allow for mechanical, biological and chemical filtration, and will also deliver oxygenated water for the aquatic fellows.

So, what’s the best aquarium internal filter?
From our reviews, we find the Fluval U4 Underwater Filter, the best overall aquarium internal filter. It offers a 3-stage filtration process, 3-way water flow control and it comes with preloaded 2 foam pads, 2 poly/carbon cartridges, and 40 grams biomax.

Nevertheless, it also has very simple and convenient installation. To crown it all, this high-quality device comes with a friendly price tag that makes it affordable even for a low budget plan.  Give your aquatic home the best safe and healthy environment.