Best Aquarium Filter for 20 Gallon Tank

Best Aquarium Filter for 20 Gallon Tank

When selecting the best aquarium filter for a 20 gallon tank, there are a couple of things you should consider. The first thing to consider is the maximum rated capacity of the filter. Selecting a filter with a maximum capacity equal to the size of your tank might not be the best option. In most cases you should pick a filter that is rated to handle a slightly larger volume of water than your aquarium contains.

Best Aquarium Filter for 20 Gallon Tank

 Aqueon QuietFlow LED PRO 20 Aquarium Power FilterAqueon QuietFlow LED PRO 20 Aquarium Power Filter
 Marineland Penguin 150 BIO-Wheel Power FilterMarineland Penguin 150 BIO-Wheel Power Filter
 AquaClear 30 Aquarium Power FilterAquaClear 30 Power Filter
 Tetra Whisper EX30 Filtration SystemTetra Whisper EX30
 Aqueon Quietflow 30 Internal Filter


Choosing an Aquarium Filter

The reason you should choose a filter powerful enough for your tank, is that a filters ability to function properly is dependent on a number of factors. One of these factors is how densely you plan to stock your tank. If you add too many fish to your aquarium, and the filter is underpowered you will run the risk of having cloudy water and unhealthy fish.

And even the type of fish you plan to keep in your aquarium may require a more powerful filter. Goldfish are a good example of one such fish, since they are well known for producing a lot of waste. And some species of fish are just messy eaters. A planted aquarium may also add extra load to your filter by contributing extra detritus to the water as the plant’s decay.

Another thing to be aware of when deciding on a filter for your 20-gallon tank, is filter media replacement costs. A low cost filter might cost you more in the long run, especially if the filter media is costly to replace. A low cost aquarium filter may also have a filter substrate that is more prone to clogging. And this could cause you to have to replace your filter media more often, which will add to the lifetime costs of maintaining your tank.

Aquarium filters come with a wide range of options, some of these features will make a filter more effective, while others are just nice to have. When deciding on which filter is right for you, make sure you pick the most effective filter for your aquarium.


Best Aquarium Filter for 20 Gallon Long Tank



Aqueon QuietFlow LED PRO 20 Aquarium Power Filter

Aqueon QuietFlow LED PRO 20 Aquarium Power Filter Package

The Aqueon QuietFlow LED PRO 20 (Buy Online) is one of the best power filters for a 20-gallon aquarium. I have been using an Aqueon QuietFlow on my 20-gallon tank for over 4 years. It offers great performance for the price and has served my needs well. This filter runs much quieter than the other filters I have used in the past. And it has been very easy to clean and maintain.

The Aqueon QuietFlow power filter uses a five-stage system to keep an aquariums water crystal clear. The first stage uses floss to remove large particles from the water, while the second stage uses activated carbon to remove toxins and odors. The final stages are somewhat unique to the Aqueon QuietFlow line.


Stage three uses a patented Bio-Holster to remove ammonia and nitrites. Stage four uses a diffuser to introduce oxygen into the water. The diffuser also reduces splashing which helps this filter live up to its QuietFlow moniker. Stage five is a slot for an optional filter pad, either a carbon pad or an ammonia or phosphate reducer can be added if water conditions warrant it.

Another unique feature of the Aqueon QuietFlow LED PRO 20 is the LED indicator light on top of the filter unit. The LED indicator light will blink when the filter media needs to be changed, this might help those of us who put off filter maintenance. I am still running the original Aqueon QuietFlow 20 on my tank, but this feature would sure give me a strong push to keep up with regular filter changes.

Aqueon Replacement Filter Cartridges Medium Pack of 3

As for filter replacement costs, the Aqueon Replacement Filter Cartridges Medium Pack of 3 (Buy Online) usually costs less than ten dollars at full price. The recommended filter replacement time listed is 4-6 weeks. In my case, I can stretch that out to 2 months, though your mileage may vary depending on your aquariums conditions.

  • Price
  • Performance
  • Quiet
  • Easy Maintenance
  • Sensitive LED Indicator




Marineland Penguin 150 BIO-Wheel Power Filter

Marineland Penguin 150 BIO-Wheel Power Filter Package

The Marineland Penguin 150 BIO-Wheel Power Filter (Buy Online) can cycle 150 gallons per hour, which makes it well suited for a 20-30 gallon tank. This filter uses a three-stage filtration process, consisting of a floss and activated carbon filter alongside the patented BIO-Wheel. As with most filters, the floss handles mechanical filtration while the carbon handles the chemical filtration process.

The unique part of this filter is the BIO-Wheel. The BIO-Wheel provides biological filtration along with aeration. As the filter ejects water over the BIO-Wheel the wheel spins, exposing the whole surface of the wheel to water.


The BIO-Wheels key function is to provide a place for nitrifying bacteria to colonize. The BIO-Wheel will also make changing the floss/carbon filter much less of an issue. In most cases a filter change can remove a large portion of the nitrifying bacteria. The BIO-Wheel can maintain biological filtration while your new filter media is being colonized. As long as you don’t change the filter pad and the BIO-Wheel at the same time, you can avoid damaging your tanks nitrogen cycle.

A BIO-Wheel will require some maintenance, mostly you will have to make sure it’s clean and it keeps moving smoothly. The BIO-Wheel will also have to be replaced, but not as often as the other filter media. Even though it can add a little more work, the benefits of a BIO-Wheel easily make this feature a good investment for the health of your aquarium.

Marineland Rite-Size Bonded Filter Sleeve Three-Pack for Penguin 150 125 Power Filters

The Marineland Rite-Size Bonded Filter Sleeve Three-Pack (Buy Online) for Penguin 150/125 Power Filters are priced at about ten dollars, and should be replaced every 2-4 weeks. The BIO-Wheel replacement cost is less than eight dollars, and it will only have to be replaced infrequently. Parts for Marineland filters are readily available, which makes this filter perfect for someone who likes to do DIY repairs.

I have used Marineland BIO-Wheel filters in the past, and they are always at the top of my list when I shop for a new filter. Marineland has produced quality filters for many years, ranging from entry level hobbyist filters all the way up to pro level filtration systems.

  • BIO-Wheel Provides Excellent Aeration
  • Good Biological Filtration
  • Part Readily Available
  • Noisy




AquaClear 30 Review

AquaClear 30 Power Filter Package

The AquaClear 30 Power Filter (Buy Online) can easily filter aquariums ranging from 10-30 gallons. The AquaClear 30 cycles 150 gallons per hour. The unique thing about this filter is the patented flow control, which can reduce the flow to less than 100 gallons per hour. This feature will allow you to use this filter on a wide variety of tanks.

Another nice bonus about the flow control is that reducing the flow can greatly reduce any filter noise. You can also set the flow control on the low setting for small or young fish that don’t like turbulent water.


The AquaClear 30 uses your standard three-stage filtration process. Mechanical filtration is handled by a large replaceable foam filter. Activated carbon takes care of all of the chemical filtration. And biological filtration occurs throughout the filter since bacteria will colonize all of the filter media.

The unique part of the filtration compartment is the media basket, which prevents any water from bypassing the filter media. This can be especially helpful if a filter change was put off, and the filter is a little dirtier than normal. In other filters, water will sometimes go around or over the filter under those circumstances.

AquaClear 30 Foam Filter

Replacement filter media is very affordable, AquaClear 30 Foam Filter Inserts (Buy Online) are available for under three dollars each. Foam filters are also more durable and they are usually more reusable than floss. Because of this you can get away with rinsing out a sponge filter instead of having to do a full replacement every time.

AquaClear 30 Carbon Filters

AquaClear 30 Carbon Filters are sold separately for under three dollars each. Unlike foam filters carbon filters can’t be reused. So having the chemical filter come as a separate insert is a nice feature. It will help maintain the nitrogen cycle since you won’t have to change all of the filter media at once .

  • Reliable
  • Adjustable
  • Quiet
  • Low Filter Replacement Costs
  • Higher Upfront Cost




Aqueon Quietflow 30 Internal Filter Review

Aqueon QuietFlow 30 Internal Power Filter, up to 30 gallon

The Aqueon Quietflow 30 Internal Filter (Buy Online) is a nice choice if you don’t want to have your filter mounted on the outside of your tank. In some cases, you might not have enough clearance around your tank. Or for aesthetic reasons you might prefer not to have the filter sticking out of the aquarium.

The Aqueon Quietflow 30 Internal Filter has a flow rate of 142 gallons per hour. This filter can be used as a primary filter on tanks ranging from 20-30 gallons. The flow is also adjustable in a variety of ways.


First, you can control the flow rate, which is great if your tank doesn’t need the filters peak capacity. You can also change the flow direction and height simply buy adjusting the output nozzle to any desired position. The filter unit can also be placed in a horizontal or vertical orientation, which is nice for finding a place to keep the filter out of sight.

This filter uses a three-stage filtration process combined in a single filter cartridge. The first stage uses a foam filter to remove any particles from the water. Activated carbon takes care of chemical filtration. And finally, the patented BioGrid handles biological filtration.

Large Aqueon QuietFlow Internal Replacement Filter Cartridge

The Aqueon Quietflow 30 Internal Filter uses a single Large Aqueon QuietFlow Internal Replacement Filter Cartridge (Buy Online), which come in packs of two for less than ten dollars. The recommended replacement period is 30 days. This is a little on the low side, since the filter cartridge is smaller than comparable external filter media.

Filter maintenance will also be slightly more involved, since you will have to remove the whole filter assembly from the water. While there will be some added work, changing the filter cartridge is as simple as any other filter.

  • Versatile
  • Quiet
  • Reliable
  • Harder to Maintain



Tetra Whisper EX30 Review

Whisper EX30 Package

The Tetra Whisper EX30 (Buy Online) is an excellent filter with a variety of innovative features. The EX30 was designed to be extremely reliable and easy to maintain. The filter is well designed and has a more modern streamlined look. As with all things Tetra makes their products are built to last for years. The EX30 is ready to go right out of the box, which makes it a great filter for beginners.

The Tetra Whisper EX30 has an impressive flow rate of 160 gallons per hour, which makes it one of the more powerful filters in it’s class. The internal design of the filter also prevents debris buildup via a continuous flushing action. This feature alone will limit the chance you will ever have to manually remove debris from the filter. The intake of the filter is also well designed with smaller openings, which is nice if you have smaller fish.


The filter uses a three-stage filtration process. A convenient filter cartridge carrier holds the combined first and second stage floss/carbon filter. The filter carrier makes inserting the filter media into the unit a breeze, while also preventing any filter bypass issues.

The third stage is the Bio-Scrubber which as the name suggests provides the biological filtration. I personally like the design of the Bio-Scrubber, which uses individual circular pads with protruding fingers to add surface area for bacterial colonization. The Bio-Scrubber also never has to be changed, this will allow the bacteria colonies to be left undisturbed during regular filter maintenance.

Tetra Large Replacement Filters

The Tetra Large Replacement Filters (Buy Online) come in packs of four and usually cost less than fifteen dollars. They are rated for 40-60 days of use, and each filter cartridge comes with a new technology called Tetra Timestrip. The Timestrip is mounted in a specially designed compartment on top of the filters lid, and it will indicate how long it has been since the last filter change.

Unlike electronic methods of monitoring filter lifespan, the Timestrip is just a time indicator. The Timestrip technology is a chemical process that is contained in a thin strip, which is activated by pressing a small bubble to start the reaction. The strip then slowly displays a red bar similar to a thermometer, to visibly show the time since the last filter change.

I personally like this kind of indicator compared to the electronic alternatives, since the chemical reaction is just time-based. So any false positives will be kept to a minimum since no interaction with the aquarium’s water is needed. For the most part ownership and maintenance of this filter seems very well thought out.

  • Powerful
  • Easy to Maintain
  • Innovative
  • Modern Design
  • Replacement Filter Cartridge Costs



Mark Young
Mark has worked with a wide range animals for over 10 years, and he regularly volunteers at his local animal shelter. Mark has decided to share his years of knowledge by writing helpful guides for both new and experienced pet owners