7 Best Filters for 20 Gallon Tank: A Complete Buyers Guide

You may never want fish and aqua plants to die in your 20-gallon tank, do you? And in order to ignore this tragic situation, you need to focus on taking proper care of the plants and fish inside the aquarium. 

In such a case, the right filter can help you, allowing the water to remain fresh and creating a healthy environment for the fish. 

On the other hand, if the filter doesn’t suit the aquarium you have at your home, it creates trouble for fish and aqua plants to stay alive due to poor water conditions. And so, going with the best filter makes too much sense. Get it? 

In today’s article, we will inform you about the 7 best filters for 20 gallon tank with detailed information. Are you ready to choose the right one? 

7 Best Filters For 20 Gallon Tank

1.AquaClear 50 Power Filter,80 GPH to 100 GHP
2.Fluval C3 Power Filter153 GPH
3.Tetra Whisper EX 30 Filter For 20 To 30 Gallon aquariums160 GPH
4.Marineland Magnum Polishing Internal Canister Filter290 GPH
5.Polar Aurora Free Media 265GPH265 GPH
6. Marina S20 Power Filter92 GPH
7.Penn-Plax Cascade 500 Aquarium115 GPH

What Are the Types of Types of Aquarium Filters?

Before buying one, you should know the type of aquarium filter available on the market. Why? This will help you choose suitable filters for your aquarium. Otherwise, your money spent on the filter might go in vain. 

Ideally, three are three types of aquarium filters based on their functionality. These are;  mechanical, chemical, and biological filters. Now, let’s have an overview of how the aquarium filters work in order to ensure the proper growth of the fish and aqua plants. 

Mechanical Aquarium Filter

This is one of the most common aquarium filters used to remove stuff like fish poop, dust, and wasted food, which are precisely visible inside the aquarium. 

The primary duty of the mechanical aquarium filters is to remove solid particles, which you can also remove physically, but doing so might not be so effective. 

In most cases, you will find the objects just mentioned floating inside an aquarium that looks nasty for fish and aqua plants. 

So, here, the mechanical aquarium filter can help you get crystal-clear water. And when it comes to improving the water quality, the mechanical aquarium filter can also play a leading role. 

Chemical Aquarium Filter

We see chemical additives used in chemical filtration to remove impurities from the aquarium. Three different types of chemical additives come into play in chemical filtration. 

For example, activated carbon is one of the key elements used in the chemical filter in order to help fish and plants get rid of toxins in the water. 

Ammonia can be a real threat to the fish inside the aquarium. But luckily, the chemical filter medium can keep the water in the aquarium safe from ammonia. 

And we often see chemical filtration used with other types of filtrations to maintain the cleanliness of the water. 

Biological Aquarium Filter

When removing excessive ammonia from the water inside the aquarium filter, the biological aquarium filter can come into play. 

We see that beneficial bacteria are used in the biological aquarium to kill the harmful bacteria or make the bacteria less dangerous to the water. 

For example, nitrifying bacteria can exist in the biological aquarium filter, which can play a decent role in making nitrate lose its functionality in water. 

You will find biological filtration in most aquarium filters on the market. So what does this mean?

If you go with the robust biological filtration for your aquarium, you don’t need to worry about the toxic biological spike. 

And needless to say, this can be very beneficial for your livestock. And when establishing stability in your tank, the biological filtration is quite up to the mark. 

Factors to Consider When Choosing a Filter for a 20-Gallon Tank

Buying a random filter for your 20-gallon tank will provide little value. But have you ever wondered what to consider when choosing a filter for a 20-gallon tank? No worries! We’ll cover this for you. 

Flow Rate

Due to some valid reasons, you need to be sure about the flow rate of the aquarium filter you want to buy. The flow rate of a filter means the quantity of water that can flow through the filter in a certain amount of time. 

In most cases, the flow rate is considered as GPH, which means Gallon Per Hour. Now, depending on your chosen filter, the gallon per hour or the filter’s flow rate might vary. 

And at the end of the day, the GHP should be suitable for the type of aquarium filter you have. Experts recommend a flow rate of 80-100 GPH for a 20-gallon aquarium tank. So, what does this mean? Well, the GHP should be 4 based on each gallon of water in the tank. 

In addition, it won’t be wise to go with too much or too little flow rate of the filter. Why? This is because if the flow rate is too low, the filter might be unable to remove harmful particles from the water. 

Similarly, if the flow rate is too high, it can create trouble for the fish and aqua plants.

Types of Filtrations

As you are supposed to know, there are different types of filtrations. And when it comes to choosing a filter for your aquarium, you need to determine exactly what kind of filtration you want. 

For example, you can have the chemical, biological, or mechanical filter separately or a combination. 

In addition, you will find a bunch of filters out there on the market. Some of the most common are; hang-on-back filters, sponge filters, canister filters, internal filters, box filters, etc. Each type of aquarium filter has some pros and cons. 

Easy Maintenance 

You should avoid facing hustle when maintaining your aquarium filter. That’s why it is always wise to go with a filter that is easy to maintain. 

This means using a filter that is easy to maintain and clean anytime. And luckily, you will find modern-day aquarium filters that are super easy to maintain. 

Compatibility with the tank

Not all filters are suitable for all types of tanks. And so, you should be careful when it comes to buying one. For example, the bigger the tank size, the more filter flow rate it requires. 

At the same time, the type of fish or aqua plants in your tank should also consider choosing the right water filter. 

What Are the 7 Best Filters for 20 Gallon Tanks? 

You’ll always find a good number of 20-gallon tank filters on the market. However, not all the filters regarding filtration efficiency are up to the mark. We researched in-depth and made a shortlist of the 7 best filters for a 20-gallon tank. 

1. AquaClear 50 Power Filter


If you are searching for an aquarium filter that comes off multiple filtrations with an affordable price range, the AquaClear 50 power filter can be a decent choice. The three-stage filtration process (Mechanica, chemical, biological) allows you to ensure good water quality inside the tank. 

In addition, according to the manufacturer, the filtration system of the AquaClear 50 power filter is seven times larger compared to other aquarium filters on the market. 

Thanks to the elements like Poly Foam, Biomax and Activated Charcoal made, the filter is effective, ensuring no harmful bacteria and visible particles in the tank. 

One of the specialties of the filter is it comes with a unique waterfall design, which allows the water to come back to the tank, hardly making any noise. 

And due to this, it is possible to produce gentle water flow, which is always helpful for the fish and different aqua plants. You’ll get a flow rate of 80 GPH to 100 GHP with the filter for your 20-gallon tank. 

What’s the price? 

The AquaClear 50 power filter on Amazon is $25 for a 20-50 gallon tank. Here you can also check the latest price of the filter on Amazon by clicking here


  • Lower operation costs.
  • Easy installation and maintenance. 
  • Lower noise level. 
  • Water flow adjustability feature. 
  • Parented Re-filtration system. 


  • Needs consistent maintenance. 
  • Motor sitting outside of the aquarium. 

2. Fluval C3 Power Filter

Fluval C3 Power Filter

One of the first things that impress you about the Fluval C3 Power Filter is its five stages of filtration. The stages include; foam, polyester, carbon, bio-screen, and n-nodes. In addition, you can have three important types of filtration at a time: mechanical, chemical, and biological filtrations.

You will have the mechanical filtrations in the first two stages. Next, in the third stage, chemical filtration takes place. And in the very last two stages, you can experience the biological filtrations. 

In addition, the versatile design of the aquarium filter makes it more convenient to use or maintain. Besides, the patented filtration system can produce gentle water flow, suitable for delicate fish and aqua plants. The maximum flow rate is 153 US Gal/H.

What’s the price? 

The Fluval C3 power filter on Amazon is $48 for a 20-gallon tank. Here you can also check the latest price of the filter on Amazon by clicking here


  • Adjustable flow rate feature. 
  • Super easy to clean. 
  • Pop-up cleaning indicator. 
  • Impressive suction power. 
  • Provides a higher filtration surface. 


  • The noise level could be more satisfying. 
  • Needs regular maintenance. 

3. Tetra Whisper Ex 30 Filter for 20 to 30 Gallon Aquariums

This is another effective multi-stage filtration aquarium filter, allowing you to ensure proper water conditions inside the aquarium. 

And as the name suggests, you can have a whisper-clear filtration process with the help of the Tetra Whisper EX 40 filter, which makes the filter more convenient to use.

Additionally, when it comes to preventing debris build-up, the ‘Continuous Flow’ comes into play on a large scale by removing the harmful object in the 20-gallon tank. 

Also, thanks to the bio-scrubber used to remove harmful ammonia and nitrites. Besides, the optimal design helps the filter stay clog-free for a long time. 

The flow rate for the 20-gallon tank is 160 GPH, which according to the manufacturer, is scientifically engineered water flow.

What’s the price? 

The Tetra Whisper EX 30 power filter on Amazon is $20 for a 20-30 gallon tank. Here you can also check the latest price of the filter on Amazon by clicking here


  • Provides maximum oxygenation.
  • Easy to clean or maintain. 
  • Simple installation process. 
  • Impressive suction power. 
  • Usable for turtle tanks. 


  • Too high a flow rate might cause trouble for some fish.
  • A bit noisy. 

4. Marineland Magnum Polishing Internal Canister Filter

MarineLand Magnum Polishing Internal Canister Filter

If you are looking forward to having the most versatile filter for your aquarium, then the Marineland Magnum Polishing Internal Canister Filter can be a better choice. 

Comes with customizable filter media, the aquarium filter is quite efficient when it comes to improving the quality of water. 

In addition, the filter’s flow rate is quite high, around 290 GPH. But yes, as you can customize or control the flow rate, you are not supposed to face major issues. 

The three-stage filtration process removes the harmful particles from the tank and creates a healthy environment for fish and aqua plants. 

What’s the price? 

The Marineland Magnum Polishing Internal Canister filter on Amazon is $85 for a 20-gallon tank. Here you can also check the latest price of the filter on Amazon by clicking here


  • Easy installation and maintenance. 
  • Comes with reliable media chamber houses. 
  • No back flash. 
  • Satisfying suction power.
  • Micron water polishing. 


  • Too strong flow rate. 
  • Take more space where it is located. 

5. Polar Aurora Free Media 265GPH

Polar Aurora Free Media 265GPH 370GPH 525GPH External Aquarium Filter

The Polar Aurora Free filter has three flexible media trays, making filtration even more effective. 

In addition, as it is a canister filter, you are supposed to have high water pressure, which can help remove food waste, poop, and other elements which can turn into bacteria. 

Moreover, the media-storing capacity helps the water media to get in touch with the water in the tank more comprehensively. 

Besides, you will also find O-ring comes with a filter, which can avoid the issue of uneven filter leakage.

The filter’s flow rate is 265 GPH for the 75-gallon tank size, which is bare enough to ensure water quality. 

What’s the price? 

The Polar Aurora Free Media 265 GPH filter on Amazon is $79.99 for a 20-gallon tank. Here you can also check the latest price of the filter on Amazon by clicking here. 


  • No need for manual siphoning.
  • Easy setup and maintenance. 
  • High-powerful filtration media. 
  • Comes with customizable filtration. 
  • Super quiet. 


  • Comparatively smaller filter box.
  • Issues with the indicator light. 

6. Marina S20 Power Filter


The Marina S20 can be a budget-friendly aquarium filter with an adjustable flow control feature. Besides, the filter takes up less space and is super easy to maintain. 

If you worry about the noise of the filter of a 20-gallon tank, you will find the Marina S20 super helpful in this case, allowing you to filter the water inside the tank, hardly making any noise.

The aquarium filter is also super effective regarding the flow rate, depending on the gallon of water in your tank. 

The three filter cartridges remove your worry about ensuring a suitable environment inside the aquarium for fish. The filter has a flow rate of 92 GPH. 

What’s the price? 

The Marina S20 Power filter on Amazon is $25 for a 20-gallon tank. Here you can also check the latest price of the filter on Amazon by clicking here


  • Easy to clean. 
  • Impressive suction ability. 
  • Suitable filter capacity. 
  • A bunch of filtration media. 
  • Suitable for small aquariums. 


  • The noise quality could have been better. 
  • Needs regular maintenance. 

7. Penn-Plax Cascade 500 Aquarium

Penn-Plax Cascade 500 Aquarium Canister Filter

Activated carbon is one of the most effective filtration methods, and that’s why the Penn-Plax Cascade is a convenient filter for a 20-gallon tank. 

The multi-stage filtration process, along with a combination of the three types of filtration, the filter has it all for improving water quality inside the tank. 

It won’t matter whether you have a saltwater or freshwater tank; the Penn-Plax Cascade aquarium is equally helpful.  

Thanks to the large capacity media basket for allowing control over customizable filtration. The flow rate is 115 GPH which is undoubtedly impressive for a 20-gallon tank.

What’s the price? 

The Penn-Plax Cascade 500 Aquarium filter on Amazon is $103 for a 20-gallon tank. Here you can also check the latest price of the filter on Amazon by clicking here


  • Allows simple and quick prime. 
  • Comes with a directional Spout.
  • Easy setup and simple maintenance. 
  • Impressive suction power.
  • Comes with adjustable valves. 


  • A bit loud. 
  • It needs priming. 


Now, you must have a precise idea regarding the best filters for 20 gallon tank. So if you decide to purchase one, this article can guide you. 

You may never want to buy aquarium filters frequently. And that’s why it is essential to take time and choose the suitable one based on your tank type. 

After all, know what you need, the kind of fish and plants inside the tank. Additionally, no matter what filter you choose, ensure the manufacturer is quite up to the mark in case of customer support. 

This will help you fix any issues with the filter once you start using it. So, what filter have you found more convenient for your 20-gallon tank? 

Sifatul Shohan

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