April 27

Best 20-gallon Aquarium Filter Reviews


20 gallon fish tank filter

A 20-gallon fish tank can easily accommodate 15 to small fishes which makes it essential to clean the aquarium regularly. Without the right filtration system and maintenance, the water quickly becomes dirty and the aquatic ecosystem cannot thrive properly. A rightly chosen 20-gallon fish tank filter can keep the water clear for weeks on end.

There are a few different types of filters for a 20-gallon aquarium. Each has its strengths and weaknesses. We will look at the best filters available in the market today and highlight the pros and cons so that you can make a more informed decision.

20-gallon Aquarium Filter Reviews 2021

1. Whisper IQ Power Filter

Whisper IQ Power Filter


The Whisper IQ Power Filter by Tetra for 20 gallon aquarium utilises medium filter cartridges. The Stay Clean Technology used in this filter provides healthier fish and easier maintenance. The flow can be reduced from 130 GPH to 10 GPH for Bettas, plants and other low flow needs.

Whisper IQ uses a sound barrier to decouple the motor from the filter. This, along with vibration dampening technology keeps the sound below 40 decibels. No priming is required to start the submerged motor. The intake can telescope up or down as per the needs of your aquarium.

The parts included are motor assembly, tube assembly, dampeners, impeller and bio-grid. All replacement parts are readily available in the market.


  • Durable
  • Quiet (<40 decibels)
  • Easy to use
  • Priming not needed
  • Flow control between 10-130 GPH
  • Adjustable intake


  • It can make strange vibrating noises occasionally

What makes this aquarium filter great is the ability to adjust the flow between 10 and 130 GPH. The manufacturer Tetra is also quite reliable since they have been in the business for 50 years. Since it is self-priming, you can just leave it alone and let it do its job once you have installed it. If you want a self-priming filter with adjustable intake, this filter will not disappoint.

2. Marineland Penguin Power Filter w/ Multi-Stage Filtration

Marineland Penguin Power Filter w/ Multi-Stage Filtration


The flow rate of this filter is 150 GPH which is perfect for all aquariums up to 30-gallon. The filter uses the Rite-Size B cartridge that contains Black Diamond Premium Activated Carbon for more efficiency.

The three-stage filter system functions pretty efficiently. The cartridges do the chemical filtration while the biological filtration is done by the patented BIO-Wheel. The BIO-Wheel is good at removing toxic nitrite and ammonia.

This filter features adjustable mid-level intake strainers and two-piece vented covers which are noise reducing.


    • Three-stage filtration system
    • Adjustable mid-level intake
    • two slots for filter cartridges


    • Instructions for installing could have been a little clearer

    This filter has two slots for the filter cartridges which means double the filtering power. You could also keep your old filter cartridge in the back slot while replacing the front one for a couple of weeks to preserve the bacteria culture.

    The Bio-Wheel is great for biological filtration and in maintaining the aquarium bio-cycle.

    The instructions to fit the filter could have been clearer. If you are not able to follow the instructions, the filter might not fit properly, make a lot of noise and end up splashing water all over your room. You could refer to a few videos on YouTube if you are not sure how to go about it. Once you do set it up correctly, it runs really quiet. You can be sure to see clear water for a month without needing to clean the filters.

    3. Aqua Clear – Fish Tank Filter

    Aqua Clear – Fish Tank Filter button

    The Aqua Clear Fish Tank Filter has a filtration system for a 20-gallon aquarium that allows the filter media to have superior contact time. The pump is energy efficient, lowering operating costs.

    The installation is quick and easy. The filtration volume is up to 7 times larger than similar filters from other brands. The filter is very efficient for continuous biological filtration as it is equipped with Activated Carbon Filter, AquaClear Foam, BioMax and Cycle Guard. It is also backed by a 2-year warranty.


    • Patented AquaClear filtration system for controlling the flow rate
    • Mechanical, chemical, and biological filtration
    • Preserves beneficial bacteria for a toxin-free environment
    • Energy efficient
    • 2-year warranty


    • Can be noisy at times

    This filter does not use a cartridge system so the bacteria culture is well preserved which could otherwise take weeks to generate. There are not too many drawbacks to this filter. It could get noisy occasionally so you should ensure that all parts have been fitted well.

    4. Fluval 106 Canister Filter

    The Fluval 106 Canister Filter is an external filter for 20 gallon aquariums. A great intake strainer and a double-layered mesh screen ensure that the filter will not get clogged too easily.

    The flow rate is adjustable with a maximum of 145 GPH. The shape of the Fluval 106 is unique which means it can hold up to 30% more water than other same-sized circular filters.

    Priming can be easily done with the press of a button. It is pretty easy to clean the filter. The lid has single motion lift-off clamps which makes it easy to get the lid on and off. The filter is pretty quiet since it uses a noise dampening impeller.

    Despite its small size, it still has a 3-stage filtration. The removable media baskets can be easily accessed and customized. Since this is an external filter, the space inside the aquarium is completely left for the fish and plants. You will need a shelf for the filter though.


    • 3 stage filtration system
    • easy maintenance
    • instant primer feature
    • does not clog easily
    • saves space inside the aquarium


    • Leaks may occur with prolonged use

    For a 20-gallon fish tank, the Fluval 106 Canister Filter is a decent buy. If easy maintenance and the external filter are what you are looking for, this filter is definitely worth considering.

    5. Fluval C Power Filter

    The Fluval C Power Filter is available in 3 sizes- C2, C3 and C4. The C2 model discussed here is the smallest at 119 GPH and is suitable for an aquarium with a size below 30 gallons.

    The filter has a 5-stage filtration system- 2 mechanical, 1 chemical and 2 biological stages. The filtering process starts with poly/foam pad then goes on to chemical activated carbon insert and finally bio screen biological C nodes.

    The parts included are filter cover, filter case, levelling device, c-nodes, “u” tube, telescopic intake tube, bio-screen, mechanical frame, chemical basket, impeller cover assembly, impeller, biological trickle chamber with cover, poly/foam pad, activated carbon and motor unit with seal ring.


    • Five-stage filtration
    • Affordable
    • Easy maintenance
    • Large capacity
    • Quiet


    • Multiple parts need to be replaced at different times so it may be hard to keep track.

    The Fluval C Power filter is pretty cheap considering it offers a five-stage filtration system and large capacity. If maintenance is not going to be an issue for you, this is the filter you should invest in.

    6. Whisper In-Tank Filter with BioScrubber for Aquariums

    Whisper In-Tank Filter with BioScrubber for Aquariums


    The Whisper In-Tank filter is the cheapest on this list. Measuring 4.2 x 4 x 8 inches, it acts as both a filter and pump.

    The unique selling point about this filter it’s BioScrubber and Bio-bag filter cartridges which provide effective and eco-friendly filtration. The design is simple. You can install it with a hanger and suction or two suction cups depending on where you want to place it. For cleaning, you will need to remove the bottom to access the impeller.

    The motor is inside the water so the filter is very quiet.


    • Inexpensive
    • Simple design
    • Biological filtration
    • Priming not needed


    • Impellers may be too big

    It can come as a surprise how something with such a simple design can work so well. You should leave at least 2 inches of room from the rim of the tank. Or else your tank will overflow. The filter pads are extremely cheap and should be replaced as often as necessary. Considering the cost and simple design, along with the reliability of Tetra, this filter is a good value for money purchase.

    Factors you should consider before buying the right tank filter for your 20-gallon aquarium

    • Placement

    Some filters are placed inside the tank while some outside. Internal filters need to be completely submerged in the water to work correctly. External filters draw the water out of the aquarium using a lift tube. The water is pushed through a series of filter media before being pumped back into the fish tank. You can choose depending on how much space you have, both inside the aquarium and outside.

    • Priming

    Priming basically means filling the entire tank and filter with water before plugging it on. Without priming, the filter will be running with air in the tubing instead of water. Some filters have self-priming while others need to be primed with the press of a button. There are other simple filters that do not need to be primed at all since the filter remains well inside the tank.

    • Filtering process

    Most quality filters come with 3 stage filtering process which includes mechanical, chemical, and biological filtering. Mechanical filtering is usually done with some foam pad or mesh. Chemical filtering is done with activated carbon filters. Biological filtering is mainly to provide enough surface area for good bacteria to grow and break down toxins like ammonia and nitrites.


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