Top 5 Best Filter For 20 Gallon Tank You Should Not Miss

A 20-gallon fish tank can comfortably house 15 small fishes, but it is necessary to clean the aquarium on a regular basis. The water soon gets polluted without the proper filtration system and treatment, and the living environment cannot be good. For weeks on end, a well-chosen 20-gallon fish tank filter will keep the water clean.

There are a few recommendations of the best filter for 20 gallon tank in the current market to choose from. Every kind has its own set of advantages and disadvantages. We will give some of the best filters on the market and show their pros and cons to make you give an easier decision.



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Top 5 Best Filter For 20 Gallon Tank – Detailed Review

Top 1: Tetra Whisper IQ Power Filter 20 Gallons

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Outstanding features:

Tetra’s Whisper IQ Power Filter uses medium filter cartridges for a 20-gallon aquarium. This filter’s Stay Clean Technology ensures healthier fish and ease of maintenance. For bettas, plants, and other low-flow uses, the flow can be decreased from 130 GPH to 10 GPH.

To decouple the motor from the filter, Whisper IQ employs a sound barrier. Thanks to a sound barrier and vibration dampening equipment, the sound is kept below 40 dB. The submerged motor does not need priming to operate. 

The intake can be adjusted to suit the needs of your aquarium. Motor assembly, tube assembly, dampeners, impeller, and bio-grid are the components used. All spare parts are widely available.

The ability to vary the flow rate between 10 and 130 GPH is what sets this aquarium filter apart. Tetra, the maker, is still very dependable, having been in operation for 50 years. You are able to leave it alone and let it do its job after you’ve built it because it’s self-priming. This filter would not disappoint you if you want a self-priming filter with modified intake.


  • Long-lasting
  • Quiet (less than 40 dB)
  • Simple to use
  • No priming is needed.
  • Flow rate ranges from 10 to 130 GPH.
  • Intake that can be modified.


  • It will sometimes make weird vibrating noises.

Top 2: Tetra Decorative ReptoFilter

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Outstanding features:

Reptiles and amphibians, like us, enjoy being in a beautiful setting. You will make them comfortable by giving them a decorative Reptofilter. These Reptofilters, of course, help you and enhance the appearance of your aquarium or terrarium.

The decorative Reptofilters operate softly, allowing you to see a waterfall without any noise in your terrarium. They’re covered with a cover for two reasons: one, to save your turtle or frog from being stuck in the waterfall filter, and two, to provide a comfortable basking platform for them. Although the waterfall works as a basking platform, its primary function is to clean the water and keep it pure and odor-free.

The installation of the filter cartridges, tubing, and pump is simple and fast with this decorative Reptofilter, which comes with thorough instructions.


  • Allows you to make a lovely waterfall and a basking area.
  • For aquariums with a capacity of up to 55 gallons
  • 4-6 inches is ideal for low water levels.
  • Replaceable bio-bags are used in a three-stage whisper filtration system.
  • Wide intake holes to avoid clogging
  • Animals are kept out of the filtration area by a locking cover

Cons: no significant drawback was found. 

Top 3: AquaClear Power Filter

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Outstanding features:

The Aqua Clear Fish Tank Filter has a filtration device for a 20-gallon aquarium that provides superior contact time for the filter media. The pump is saving-cost and saving-energy.

The setup is simple and fast. The filtration volume is up to 7 times larger than other fish tank filters. Since it is fitted with an Activated Carbon Filter, AquaClear Foam, BioMax, and Cycle Guard, the filter is very effective for continuous biological filtration. It also comes with a two-year warranty.


  • Controlling the flow rate with the patented AquaClear filtration device
  • Provides mechanical, chemical, and biological filtration
  • Beneficial bacteria are preserved for a toxin-free environment.
  • Saving-energy
  • Lifetime warranty


  • Sometimes it is noisy. 
  • AquaClear media can be very costly. You may, however, use a different form of media.

Top 4: Tetra Whisper EX Silent Multi-Stage Power Filter for Aquariums

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Outstanding features:

Tetra has long been a go-to brand for fish keepers looking for products and solutions that make their lives easier and more beautiful. 

Tetra Whisper EX30 Power Filter is a quiet multi-stage filtration system that produces clear, filtered water.  Every feature of the Whisper EX facilitates simplicity and convenience to users. This is the most user-friendly filtration system available. Outflow promotes agitation and oxygenation of the water.

Tetra EX Carbon Filters are used in Whisper EX Filtration Systems. This filter is simple to set up and does not require priming. A continuous flushing operation avoids debris accumulation. The Whisper EX70 Power Filter is ideal for aquariums with a capacity of 20 to 30 gallons. It comes with big cartridges to ensure that your power filter stays in good working order.


  • There’s a waterfall, a basking area, and a filter.
  • Hidden water filtration device that works perfectly
  • Ensures proper water distribution and aeration.
  • Filtration system of three stages


  • No significant downside was found.

Top 5: Marineland Penguin Bio-Wheel Power Filter

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Outstanding features:

This filter has a flow rate of 100 GPH, which is ideal for aquariums up to 20 gallons. For increased performance, the filter uses the Rite-Size cartridge, which contains Black Diamond Premium Activated Carbon.

The three-stage filtering system performs admirably. Chemical filtration is handled by the cartridges, while biological filtration is handled by BIO-Wheel. The BIO-Wheel is effective at separating nitrite and ammonia, all of which are poisonous.

The filter has noise-reducing two-piece vented covers and flexible mid-level intake strainers.

This filter has two slots for the filter cartridges, giving it double the filtering power. To maintain the bacteria community, keep the old filter cartridge in the back slot while removing the front one for a few weeks.

The Bio-Wheel is suitable for biological filtration and aquarium bio-cycle maintenance.

The directions for installing the filter should have been more precise. If you don’t follow the directions closely, the filter cannot fit correctly. It leads to a lot of noise and spills water all over your room. Once you do set it up correctly, it runs really quiet.


  • Filtration system with 3 stages
  • Mid-level intake that can be modified
  • Filter cartridges have two slots.


  • The directions for installing the filter should have been more precise.

Important to features

What should you consider before purchasing the best filter for a 20-gallon tank? 


Few filters are installed inside the reservoir, while others are installed outside. Internal filters must be fully immersed in water in order to operate properly. External filters pump water out of the aquarium using a lift tube. The water is filtered back into the fish tank after passing through a set of filter media. You have a lot of options, both inside and outside the aquarium, depending on your space.


Priming refers to the process of filling the tank and filter with water before turning it on. If the filter is not primed, it will run with air in the tubing instead of water. Some filters are self-priming, while others require a button press to prime. 

Filtering process

The majority of high-quality filters include a three-stage filtration mechanism that involves mechanical, chemical, and biological filtering. Mechanical filtration is typically achieved by the application of a foam pad or mesh. Activated carbon filters are used for chemical filtration. The aim of biological filtering is to provide enough surface space for beneficial bacteria to expand and break down contaminants such as ammonia and nitrites.

Best Filter For 20 Gallon Tank FAQs

Which filter can I use in a 20-gallon tank?

There are some filter choices to consider for medium-sized aquariums:

Hangs on the back filter (HOB)

When it comes to 20-gallon aquariums, HOB filters might be the best alternative. These filters slip effortlessly onto the aquarium’s side, are simple to maintain, and provide mechanical and biochemical filtration.

In contrast to bigger filter systems, they’re much less costly and quiet. Furthermore, hang-on-back filters effectively filter the water volume.

Internal Filter

Internal filters are another filtration choice for aquariums, but their performance does not equate to that of HOB filters.

Internal filters are often more difficult to clean and maintain, but they can be a reasonable alternative for small aquariums or terrariums that don’t need a lot of water flow.

Canister Filter

Canister Filters are efficient filters capable of filtration in large aquariums. You can put them outside the tank and, in comparison to HOB filters, make quite a bit of noise.

A canister filter can be overkill for a 20-gallon tank. Canister filters are suitable for aquariums bigger than 50 gallons, but smaller aquariums will be able to use them as well.

As a consequence, if you have a 20-gallon aquarium, a hang-on-back filter is best. Simply choose a HOB filter with a capacity of 20 gallons. You are able to get the filter up and running, and it is much easier to maintain in the long term.

When should your aquarium filter be cleaned?

Beginner aquarists sometimes make the mistake of cleaning the filter if they find debris. The filter’s function is to get filthy as the water becomes cleaner. Cleaning a filter should be achieved on a monthly basis, depending on the kind of setup you have.

Check to see if the water flow rate has diminished to see if the filter has clogged. That time, you should clean the filter. If there is a lot of sludge or free-floating debris in the bath, you can also disinfect it.

What should you do if your aquarium filter fails?

It’s likely that your filter will stop running for a range of reasons, any of which you can correct yourself. If the engine, impeller, or intake and outtake tubes of a filter get clogged, the filter will stop working. You can need to use your hands or gently compressed air to unclog the engine.

Power surges will also blow the filter, necessitating the purchase of a new one. It’s still a smart idea to contact a mechanic if the harm is serious.

What are the benefits of using a bigger aquarium filter?

Seasoned aquarists advocate the use of over-filtering widely for your aquarium. This is because smaller filters can easily clog, particularly if you have a lot of waste from your fish. Larger filters, on the other hand, are correlated with higher flow speeds, but the current can be diffused for fragile fish.

In conclusion, you should choose over-filtering which model from 30 gallons to 50 gallons for your 20-gallon aquariums. Hangs on the back, canister, and internal filters are available from brands including Aqua Clear, Penn Plax, and MarineLand for a medium-sized tank.

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