Best filters for 20-Gallon Fish Tanks

Category: Buying Guide 2

FILTERS FOR 20-GALLON FISH TANKSFilter is one of the most crucial parts of a fish tank. Not only does it provide the proper amount of oxygen to your fish but it also makes the water environment inside the tank cleaner and healthier.

Filters are responsible for maintaining the overall health status of the fish in the tanks and prolong their lives. However, if you do not choose the right filter, according to the size of the tank, the effectiveness will not be at 100%.

In this article particularly, we are going to give you some honest review about the best filters for 20 gallon aquariums. Being a relatively small size tank, you can pick many different types of filter, to your own reference. They include power, canister and internal filters.

They are the most popular in today’s world, due to their superior power and effectiveness over all the other types of filter. If you are a beginner and don’t have any experience with any type of aquarium filters, it is not going to be too big of a problem. However, getting some basic knowledge about aquarium filters is advisable. Without further ado, let’s get into the six best fish tank filters for 20 gallon aquarium.

1. AquaClear 20 power filter for 20 gallon fish tank

This is a power filter with the Hang-On-Back design. The product from AquaClear power filter can go very well with different sizes, unlike other types of filters that can only be used for specific tank sizes. This is because it has a larger media capacity. With the large filtration capacity, the filter is very flexible to use filter media that makes it the most favorite filter on the market. You can choose your own filter materials to work with the filter and don’t have to use ones from the manufacturer.

It comes with some filter materials like AquaClear foam, activated carbon and BioMax that are necessary for setting up a complete system with mechanical, biological, and chemical filtration. With the grid of all types of filtration provided, the filter ensures that all the water going through it is properly filtered and safe for the fish to live in.

People love to use the filter with only biological and mechanical filter media to provide the ultra-clean environment for their fish; and they only add activated carbon media to perform the chemical filtration when the aquarium water looks yellowish. The filter features a flow rate of 100 gallons per hour which is strong enough to keep a tank with 20 gallons of water clean and clear for a long period. The flow rate can be adjustable to fit various tank sizes and fish types, so don’t worry if it is too strong for your tank. The flow rate can be reduced up to 50% without interfering with its filtration efficiency because of its patented re-filtration system (Cycle Guard with BioMax). This system holds the water within it for processing multiple times when the flow rate is reduced.

The filter is very popular on the aquarium hobby and its quality is proven by thousands of hobbyists on the world. With its very affordable price, quality and customization ability, I strongly recommend this filter for creative hobbyists who want to build their own filtration system. This is also the best tank in this article for all aspects are well adjusted to be balance. No drawback is too significant to make you change your mind over to some other tank.

We can spend all day talking about the sweet spots of the product from AquaClear. The quality product keeps the water clean and clear all the time. The capacity of the filter is large so that it can contain more filter media, thus enhance the performance. Also, the filter materials are highly flexible in order for it to filter out almost all the unwanted dirt. Another plus point of the product from AquaClear is that it operates very quietly, which makes sure you would not be disturbed while your fish is being taken care of. The flow rate of the filter can be adjusted without changing its efficiency. Being easy to set up and cheap to maintain, coming with 2-year warranty, the AquaClear filter is the best choice for the 20-gallon tanks.

2. Marina Slim S20 power filter for 20-gallon aquarium

I like Marina because of their quality aquarium kits like the Marina LED aquarium kits for starters. Their quality products have satisfied most customers from the new comers to advanced hobbyists. You can easily notice that when you read the reviews of Marina’s products.

Marina Slim S20 power filter features a very compact design for easy setup, even in small spaces. It features an adjustable flow control that makes it an ideal choice for small tanks up to 20 gallons. The best feature of Marina Slim S20 power filter is that it operates so quietly but still ensures its filtration efficiency. It can start itself after installation, cleaning or power interruptions without the need of manual priming.

The only drawback of this filter is its capacity smaller than the Aquaclear 20 and you have to buy the filter cartridges for the maintenance. However, the abundance of biological filter materials (zeolite and Ceramic) included in the filter cartridges ensure that harmful nitrogenous toxins (ammonia and nitrite) are degraded and no longer harm your aquarium inhabitants. So, it is worth for your money.

3. Fluval C2 Power Filter for 20-25 gallon tanks

This is a high-quality power filter manufactured by Hagen Fluval, a well-known brand for their aquarium products. The product includes everything you need to get started: activated Carbon for chemical filtration, C-nodes for the colonization of helpful bacteria (biological filtration), and foam pad for mechanically filtering solid particles in aquarium water. The flowrate is around 119 GPH and can be adjusted flexibly throughout operation. The filter is ideal when used in 20-25 gallon tanks according to the US standards. There are 5 stages during filtration process. All the medias of the filter consist of a Fluval C2 Poly/Foam, activated carbon, C-nodes and Bio-Screen (which is a drip tray pad).

Since the 5-stage filtration process is kind of a new concept to many, i would like to make a quick description of it. The 5 stage aims to make your aquarium even more clean and clear, and provide an absolutely healthy environment for your fish to live in. The 5 stages are:

  • 1&2: poly/foam pad mechanically removes waste particles out of the water.
  • 3: activated carbon insert removes heavy meatals, odors and discolorations to keep the water clear.
  • 4: Bio-Screan trickles the water and make it well aerated and ready for biological filtration stage.
  • 5: C-Nodes provides optimal living space for helpful nitrifying bacteria, which processes nitrogenous toxins (ammonia and nitrite).

There are tons of good things you can bring up to talk about this advanced filter. The 5-stage filtration is absolutely a breakthrough in cleaning the aquarium environment. Quality product keeps the water clean and clear with great efficiency. The flow rate of the filter is adjustable, so you will not have any problem with it. The filter media is free to use, and it is easy to set up and maintain. You also don’t have to worry about the noise issues regarding most filters, since the operation of the machine is very quiet. The minor concerns about this product is the a-little-too-high price and less filtration capacity than most AquaClear filters.

4. Whisper internal filter for 20-gallon tanks

This internal filter has the flow rate of around 125 gallon per hour. This filter is designed especially for 10-20-gallon tanks. The cartridge is one pre-assembled Whisper Bio-Bag filter cartridge. It is placed and works inside the aquarium. The internal filter should be the oldest in this list. It is a traditional type of aquarium filters and a head start for those who want to dig into fish. This in-tank filter is compact, cheap, easy to install and use. Only assemble the filter, then position it inside your aquarium (submerge into the water), and the filter will do its work to keep the tank clean and clear. The filter uses a medium Whisper bio-bag cartridge and a patented Bio-scrubber pad to provide a three-stage filtration. The Whisper bio-bag cartridge is a floss pad filled with activated carbon to eliminate waste particles, odors, and discolorations in the aquarium water. The Bio-scrubber pad provides a large surface for helpful bacteria to thrive in.

According to many experienced people, the Whisper internal filter is like a 50-50 deal, for it has plenty of either pros and cons. It is dirt cheap, and has a bio-scrubber for biological filtration. There is almost no noise while it is operating because it is submerged in the water, which is the most obvious sweet point of internal filter. The Whisper product is ideal for low-level water tanks or turtle tanks, since the higher the water level is, the less effective it becomes. On the darker side, the filter will definitely take space inside the aquarium. There is less media capacity than the more advanced power and canister filters. The biological stage seems very weak during operation. Another bad thing about all internal filters is that the flow rate cannot be altered, so it is impossible for you to reduce the performance of the machine when the water is just a little dirty. You may have to use the cartridge from the manufacturer rather than custom-made ones. In another word, the performance of the filter will remain still until it breaks.

5. Fluval 106 external canister filter for 20-25-gallon tanks

The canister filter has a flow rate of about 145 gallon per hour and that number can absolutely be changed during operation. The filter is made for tanks sized at around 25 US gallons, both fresh and saltwater. There Is a total of 3 types of filtration inside the filter. The filtering media includes 4 foam pads, 1x70g carbon, 1x120g BioMax. Since this is a canister filter, there are 2 media baskets inside.

Most aquarists prefer to filter their fish tanks with canister filters despite the fact that they are usually much more expensive than power or internal filters. Unlike other canister filters which commonly goes with large or extra-large tank, the Fluval 106 canister filter is among those rated for small tanks, under 20 gallons.

The filter chamber of the Fluval 106 is larger than other comparable canister filters that are rated for the same tank sizes. It includes two large filter media baskets that is capable of accommodating a variety of filter media. Because its capacity is much bigger than other filters, it has the advantage of containing more filter materials for better filtration and less maintenance (longer periods between maintenance times). Needless to say, the filter is designed to fit in aquariums with the size up to 25 gallons and this one should be a must-have for a 20-gallon fish tank if you are picking a canister filter over all the other types.

For an advanced filter like this one, there are plenty of points that I can use to recommend it to you. The best thing about a canister filter is the excellent performance of three types of filtration. The filter has an incredibly large capacity, which is 30-50% more than round canisters. The convoluted water flow pattern inside the filter is designed for better water-media contact. What’s more, the flow rate of the machine is not only high but also adjustable. Fluval solved the noise issue in their external filter with a sound dampening impeller, so that it can operate quietly. instant priming by pressing the button on the lid is a good feature that is included in the product. Last but not the least, the product is easy to disassemble for maintenance, easy to find replacements, has a large capacity for low and maintenance and it comes with a 3-year warranty. The only downside of the filter should be the price because it is rather expensive than other canister filters.

6. Penn Plax Cascade 500 Canister Filter

Another canister filter with a slightly lower flow rate than the Fluval 106, at around 115 gallon per hour, and of course that flow rate can be adjusted. The filter is ideal for 20-25-gallon aquarium, both marine and freshwater. There are three types of filtration inside this filter. The filter media consists of bio-floss, bio-sponges, activated carbon to perform multi-stage filtration and completely purify your aquarium water.

Setting up and maintaining the Cascade 500 canister filter requires a little effort only. Once it is already in place, the filter works effectively and speedily to keep your fish tank in the clean and clear condition all the time. Installing the filter takes around half an hour and after spending that worthwhile 30 minutes, you should notice the changes to your aquarium in a 1-day time.

The filter has a very affordable price tag for a canister filter. it comes in a large capacity for excellent performance of three types of filtration. The flow rate, though lower than the Fluval 600, is still high and can be adjusted. It is very quick and easy to prime only by pushing the button on its top. There are flow rate control valves and easy-lift clamps for easy setup and maintenance.

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