The 10 Best Aquarium Filters 2021: Reviews & Buying Guide

An aquarium doesn’t really work without a filter, and for the sake of your fish you need the best. Here’s how you can find the best aquarium filters for your marine pets.

An aquarium isn’t simply a transparent container with some water in it for your fish and other water creatures. To make sure your fish remain happy (not to mention alive), you need to make sure that you have a proper filter working with your aquarium. The best aquarium filters can make sure the water in the fish tank remains clean regardless of the mess that inevitably comes up in the aquarium. After all, fish make waste, you may put in too much food, and algae may develop.

So which brand and model of aquarium filter should you pick? Here are some excellent options you can choose from:

Top 10 Aquarium Filter Comparison Chart

BrandSize capacityFlow rateDimensionsBiologicalChemicalMechanical 
Aqua Clear Power Filter – 110 V​60 to 110 gallons500 gph7.1 x 13.9 x 9.1 inches
Penn Plax Cascade Canister Aquarium Filter (150 gallons)Up to 150 gallons315 gph11.5 x 20.5 x 11 inches
Marineland Penguin Power Filter (350)50 to 70 gallons350 gph15.2 x 6.1 x 8 inches
Eheim Classic Series External FilterUp to 66 gallons116 gph8 x 6.3 x 14 inches
Tetra Whisper Power FilterUp to 40 gallons210 gph5.4 x 8 x 7.9 inches
Aqueon QuietFlow LED Pro Power FilterUp to 30 gallons125 gph7.6 x 4.8 x 8 inches
MarineLand MagniFlow Canister FilterUp to 100 gallons360 gph14 x 11 x 18 inches
Fluval External Fish Tank FilterUp to 100 gallons383 gph7.6 x 14.5 x 17.8 inches
Aqua Clear Fish Tank FilterUp to 55 gallons200 gph4 x 9 x 8 inches
Penn Plax Cascade Canister Aquarium Filter Cascade® 10008 x 4 inches

This is actually available in several sizes, and if your tank capacity is within 60 to 110 gallons, the 110V version is what you want. Its pump can work in water temperatures up to 35 degrees C. 

This features the CycleGuard Multi-Stage Filtration System, which allows for biological, chemical, and mechanical filtration. At the bottom you have the AquaClear Foam insert, which provides a surface for beneficial bacteria and also removes debris for optimum water distribution. In the middle, you get the AquaClear Activated Carbon Filter Inserts that contain high-quality “research-grade” carbon to remove impurities and odors. At the top, you have the AquaClear BioMax Filter Inserts with the BioMax ceramic rings that also offers a place for the helpful bacteria to thrive in. 

This works very simply, actually. The filter has an extension tube through which the drawn water from the tank goes into the filter motor. This then pumps the water out. It features a U-shaped intake tube that directs the infiltered water through the various filter inserts to take out the debris and clean the water. 

This is a hang-on filter system that comes with a rather singular design, and it allows you to control the flow rate without necessarily downgrading the filter performance. When you reduce the flow rate, the filter processes more of the water a few more times to really take out the filth from the water.

Read full review of Aquaclear Power Filter

  • Installing this is fast and easy
  • Allows for mechanical, chemical, and biological filtration
  • It can filter 7 times as much water as other similar filters
  • 2-year warranty with Lifetime Guarantee on all non-replaceable parts
  • Not loud at all
  • Easy to clean
  • The instructions for assembly may be a bit hard to understand

This works for freshwater tanks, along with seawater aquariums as long as you only have fish. With its 315 gph flow rate, it’s rated for tanks up to 150 gallons. This is a heavy-duty external filter that uses a lot of tough hard plastic. 

The setup and adjustments should be easy to make, since you have swimming pool-style hose clamps and flow rate control valves. Starting it up is quick and easy as well with the quick push-button primer. Placement of the filter isn’t a problem either, with the rotational valves that can independently turn at 360 degrees. At the base you have a nicely sturdy rubber mount designed to be tip-proof. This also has an airtight seal to make sure you have a proper flow rate, and it also minimizes the noise.

This features 4 large media trays which can give you a 3-stage filtration system. You have several Cascade media options to choose from so you can take care of your mechanical, biological, and chemical filtration requirements. For example, you can get the CCF331 Poly Fiber Floss Pad to trap floating debris, the CCF329 bio-sponge that allows for the colonization of helpful bacteria, and the CCF233 Filt-A-Pack Pro-Carb to take out the bad smells, dangerous chemicals, and toxins. Some of the Cascade packages even come with free carbon, a coarse sponge, and 2 floss pads. 

This can work very quickly once you get it going. It starts filtering out the water in half an hour, and within the day your water should be noticeably cleaner.

  • Made with very hardy plastic
  • No trouble in setting it up
  • Easy to start up with the primer
  • It’s relatively quiet
  • Tip-proof base
  • Offers all types of filtration methods
  • The 1200 is better suited for smaller tanks with its 315 gph

Now this one has a flow rate of 350 gph, and it’s properly labeled as best suited for tanks with a 50 to 70-gallon capacity. If you have a smaller tank, you can go with the Penguin 200 for a 50-gallon tank, Penguin 150 for a 30-gallon, or the Penguin 100 for a 20-gallon aquarium. 

It also offers all the different filtration methods in the 3-stage filtration system. Stage 1 is for mechanical filtration, with the Penguin Rite-Size Filter Cartridge floss and the special ribbed back. Stage 2 is chemical filtration, with the Black Diamond Premium Activated carbon. Finally, Stage 3 offers biological filtration with the new BIO-Wheel that offers 50% more space to grow the beneficial bacteria.

Setting this up is somewhat easy. You just follow the manual instructions and then you can just hang this at the back of the aquarium. Before you plug it in, make sure you prime the filter with aquarium water. After you’ve installed this, you can use the mid-level strainer to adjust the water flow.

Filter maintenance for the Penguin is no hassle at all. Just clean the filter when it becomes dirty, and replace the fish tank filter cartridge every month.

Read full review of Marineland Penguin Power Filter 350

  • Strong water flow rate
  • Easy setup
  • No need to shut the filter down when replacing the cartridges
  • Sticky wheels and impellers only need 5 minutes to clean and fix
  • Quiet when you properly fill up the tank with enough water and you lower the flow rate
  • The 350 gph can be somewhat disruptive when you’re trying to get to sleep

This may be an older design but then again, you’re also opting for proven technology. This is a German brand that knows what it’s doing, although they really should improve the way they write their English instruction manuals. You’re better off checking out YouTube for videos on what you ought to do to set and start this up properly. 

We focus on the Classic 250 already comes with mechanical and biological filter media, and they’re actually easy to set up. The first level is for the biological filtration with the Eheim Substrat Pro large surface area biomedia. After that you have the filter pads for mechanical filtration. You may get a coarse filter pad along with a “polishing” filter pad, but you may be better off with a 2nd coarse filter pad instead. That’s because that fine polishing fad is so effective at filtering out fine debris that it clogs up very quickly. This then restricts your flow rate, and after a few days it’s no longer as effective as it should be in keeping your fish tank water clean.

Set it up with a 2nd coarse filter pad, and it’s great. It works, though the 116 gph is best suited for small fish. This works very well and it doesn’t leak due to the permo-elastic silicon sealing ring on the pump head. It’s quite easy to clean as well.

Read full review of EHEIM Classic External Canister Filter with Media

  • Proven technology
  • Very quiet
  • Easy to maintain with quick assembly and disassembly
  • Cheap replacement pads
  • Very durable
  • Unclear instructions in the manual
  • Can be a hassle to prime for some people

The Tetra brand has been in business for more than half a century now, so it’s fair to say they know what they’re doing. The Whisper model is designed to suit smaller fish tanks, but even their filter for a 40-gallon tank offers a 3-stage filtration system. You’ve got everything covered to make sure your aquarium water remains a healthy environment for your fish. 

This power filter model uses the Bio-Bag filter cartridges. These provide 2 functions, including filtering out tiny debris floating around in the fish tank water. At the same time, it also has activated carbon for chemical filtration so you can get of discoloration and awful smells. You also have the Bio-Foam for biological filtration to take out nitrites and ammonia. 

These cartridges are quite economical, and extremely simple to replace. All you have to do is to pull out the old cartridge and then you can just slide in the new one. 

Perhaps the most common problem with this filter among customers is that it can be rather noise when you don’t set it up properly. Plenty of people don’t seat the propeller tube assembly in the filter housing the right way. To do this correctly, you first need the 2 small notches where the propeller sits on the housing. You have to align those 2 notches properly, while you also put in enough down force to seat the tube properly. If you do this wrong, you can end up with a lot of noise. Do it right, and you won’t have any noise problem at all.

  • Adjustable water flow
  • Very affordable
  • Affordable and easy to replace cartridges
  • 3 types of filtration
  • Setup can be a bit tricky especially at first

Wouldn’t it be nicer if you have a convenient reminder regarding when you have to change the cartridge? One way to do this is to just replace them according to some arbitrary time frame. But in this power filter version, there’s an LED light that flashes to tell you that it’s time to replace your clogged cartridges. This actually checks the actual water level, so you can make sure you replace the cartridge whenever you have to.

This is also available in several sizes, including the Size 20. This is actually usable for a 30-gallon fish tank, as it comes with 125 gph. This gives you biological, chemical, and mechanical filtration. In addition, you also get some help from Aqueon specialty filter pads. 

All in all, you have 5 total stages for your filtration. You use dense floss for debris in stage 1, activated carbon for discolorations and foul odors, in stage 2, while in stage 3 the Bio-Holster gets rid of nitrites and ammonia. Stage 4 has a diffuser grid that takes out more toxins. This also adds more oxygen for the fish while it lessens the splashing. Finally, state 5 offers the specialty filter pad option, so can put in a phosphate remover, ammonia reducer, or extra carbon. 

This has a self-priming feature, so after a cleaning session (or a power outage) it can start up automatically. This also features an internal pump design, which cuts down on leaks and also reduces the noise. This is quite a durable filter, and Aqueon knows it. That’s why it comes with a lifetime warranty.

  • Powerful flow rate
  • 3 types of filtration
  • 5-stage filtration
  • LED light tells you when to replace the cartridge.
  • Durable filter with lifetime warranty
  • Quiet
  • The included sample filter isn’t as good as the large Aqueon replacement cartridges.

This Marineland Magniflow 360 Canister Filter all 3 filtration methods, and then some. The bottom layer works for mechanical filtration, with the pads cleaned and rinsed every 3 weeks. After 9 weeks, you should replace it to make sure it screens out particles properly. 

Next is the carbon bag, with the Black Diamond premium activated carbon working as your chemical filtration system. You’ll just need to replace the carbon bag each month. After that, you have biological filtration with the use of bio-filter balls and ceramic rings to help grow the beneficial bacteria. Finally, you have the “water polishing” layer that gets rid of the fine debris so your water turns clear as glass. You just need to replace the polishing filter pad every 3 weeks.

This works for both saltwater and freshwater tanks. It gives a strong seal with the top-sealing gasket, while the lid is easy to remove so you can replace the filter with no trouble. When it’s maintenance time, you have the quick-release valve block that stops the water flow right away. It separates from the motor housing so you can clean and replace filter pads without wasting time or spilling water. 

If you ever have the bad luck of getting a filter damaged during the delivery, you should just contact the folks at the Marineland and they will get you your damaged parts without any fuss at all.

Read full review of MarineLand MagniFlow Canister Filter

  • Comes with all 3 types of filtration method (and the pads as well)
  • Has polishing pad to give you really clear water
  • Easy enough to replace filter pads
  • The polishing pad can really clog up quickly sometimes, so you need to clean it more often.

This comes in several versions, and we focus on the 406 model that offers 383 gph and is rated for tanks up to 100 gallons. With the upgraded canister filter model, you have a more robust motor while it’s been designed to be extremely easy to use. This motor doesn’t just boost the flow rate, but its quality means you won’t have to clean it too frequently. 

Yet this still operates fairly quietly, and that’s due to the sound dampening feature in the impeller design. This is now 15% quieter than before. Even the cover on the impeller has been designed so it’s less likely to break.

The square shape of this canister filter actually holds up to 50% more water. This improves the water flow, while at the same time it also maximizes the contact between the water and the filtration media.

Read full review of Fluval External Fish Tank Filter

  • Stronger motor that doesn’t need frequent maintenance
  • Quiet operations
  • Uses Bio-Foam media for better biological filtration
  • Impeller cover may fall off unless you push down on both ends of the top to make sure it’s secure.

This is another 3-stage filtration system that makes sure all your bases are covered. At the bottom you have the AquaClear Foam Insert, which provide surfaces for beneficial bacteria. This also helps in removing debris from the fish tank water (mechanical filtration). You just need to replace this insert every two months. 

After that, you have the Activated Carbon Filter Inserts with the 100% research-grade carbon for chemical filtration. This carbon insert can be replaced every month. Finally, at the top there’s another layer of biological filtration using BioMax ceramic rings. The AquaClear BioMax Filter Insert should be replaced every 3 months.

This offers 200 gph, so it should be good for tanks up to 50 (or maybe even 55) gallons. But if that’s too strong of a flow rate for your small fish, don’t worry. You can reduce the flow rate here and it remains efficient in keeping your aquarium water clean.

Read full review of Aquaclear Power Filter

  • Fairly quiet
  • 3 types of filtration
  • Adjustable flow rate
  • Can work for saltwater (though the ceramic rings won’t work)
  • Only 2 years warranty

Now we get away from filter systems to focus on the floss pads you’re going to need if you bought the Penn Plax Cascade 700 1000 canister filter. This also works with Eheim ECCO, Eheim Pro/Pro II, AquaClear 500 and FilStar Canisters. 

Each order of these floss pads gives you 6 pieces, and with the proper maintenance you can get it to last for up to a year. These work for biological and chemical filtration, which can be expensive with other brands. Now you have a decidedly more affordable alternative.


That’s not to say this doesn’t work well—it works very well indeed. This traps particulates very well. The Filter Media Bags removes various contaminants in the water, so it looks and smells very clean. The size of the pads is just right too, so it fits into the filter tray without gaps through which water can pass through unfiltered. It’s effective enough that there’s a money-back guarantee.

  • No fuss replacements
  • Washable pads
  • A 6-pack can last for an entire year (2 to 3 months per pad)
  • This can trap particulates very well
  • It extends lifespans of carbon and biological filters
  • Fits into trays perfectly
  • The return policy can charge you with shipping costs

How Does an Aquarium Filter Work?

While the aquarium filter can aerate the fish tank water so your fish can breathe in oxygen, the main purpose of the filter is to keep the aquarium water clean. What you have to understand is that the water in the aquarium can get dirty very quickly if you don’t have a proper filter. 

The fish excrete their waste almost constantly as they swim to and fro, and their waste contains toxins that can eventually kill the fish if you don’t get rid of it. The filter can also remove harmful chemicals, excess food, decaying organic matter, and other types of particulates that can get into the water and harm your fish. 

Your filter can keep your fish tank water clean in several ways, depending on what kind of filtration methods it features:

  • Biological. This filtration method uses microorganisms and bacteria (and maybe even some types of plants and fungi) to turn the toxins in the water to something decidedly less harmful. The ammonia from the waste and from decaying matter can kill your fish, and the bacterial filters can turn it into less harmful nitrate. 

  • Chemical. This uses carbon or other chemical resins to remove toxins from the water. 

  • Mechanical. This is also called particulate or physical filtration. It works by using some sort of strainer to catch floating particles in the water. 

Your filtration system can feature more than one type of filtration method, to make sure you remove as much of the filth as possible from the water. Of course, even the most effective filtration system doesn’t take away the need for regular water changes and occasionally cleaning the fish tank. 

Aquarium Filter Types

Filters can also be categorized by their design and placement. The best design for you, however, will depend on your fish tank and your own preferences. 

  • Internal filter. This is probably what you envisioned as your aquarium filter if you’re not too familiar with the other fish tank filter types. These are somewhat small components that you usually see in a corner of the aquarium. Lots of these filters are decorated to fit in with your typical marine theme. They’re fairly inexpensive and still quite effective in preventing the buildup of debris in the water. 

  • HOB filter. HOB stands for “Hang On Back” and you’ll usually find it clipped at the back of the aquarium. It’s also a bit small, but as it hangs on the outside of the tank it doesn’t cramp up the inside of the aquarium. However, the main drawback here is that it’s not surrounded by water so it’s also somewhat noisier. Still, it’s one of the more popular types as it’s easy to install and use. It’s very effective, as it moves the water through a tube to move it through 3 filtration chambers that take out the toxins and dirt from the water. 

  • Canister filter. These are large and quite heavy, as they’re designed mainly to work for larger aquariums at least 40 gallons in size. This can either sit on the floor right by the tank, or it can also hang off the side of the aquarium like a large HOB filter. This features rather flexible intake and return pipes. It can offer 3 types of filtration, although its biological filtration effectiveness isn’t as good as its mechanical and chemical filtration. 

  • Undergravel filter. Some people think filters mess up the overall look of an aquarium, so they get an undergravel filter. This is very discreet since you put it under the gravel of the aquarium. The water still goes through the gravel, and the filter cleans out the water before it sends it right back out. This works well for smaller fish tanks, and it mainly uses mechanical filtration. It can be a bit bothersome to maintain, however. 

  • Wet dry filter. These are often used when you have several types of creatures in your tank. It’s quite versatile, as it works for reef and freshwater aquariums. There’s an internal part into which water is siphoned, and then the water is moved through the external section of the filter. This works very well for biological filtration. 

Sump filter. Technically, this isn’t really a filter. Instead, it’s a holder for all your different aquarium filter media types. In general, this type is used for saltwater tanks.

How to Clean Aquarium Filters

There’s really no single procedure that works for every brand of aquarium filter. You should get the manual for the filter and just follow the directions on how to clean it. 

However, it is true that the basic steps for cleaning an aquarium are somewhat similar across all types:

  1. Take out the water. 
  2. Unplug the filter. 
  3. Clean off the sponge or the pad you use in your filtration system. Just replace it if it’s too dirty and the replacements aren’t expensive. 
  4. Disassemble the filter and clean the casing along with all the tubes. 
  5. Put every back together, refill it, and put it back to work in your fish tank.

Buyer's Guide

Obviously with the many fish tank filter systems and designs available, you have lots of different fish tank models to choose from. How do you know which ones will be best for you? Aside from the price, you should consider the following factors.

Size and Filter Type

You generally need a specific type of aquarium filter depending on the size of your fish tank. The standard aquarium size is 20 gallons, and the normal filter for this is an HOB filter or an internal aquarium filter. These are smallish filters that should match up well with this size. 

But for bigger tanks, you will have to consider other types such as canister filters, wet dry filters, and sumps.

Ease of Installation

It’s great if setting up the filter on your tank is no problem. Sadly, that’s not always the case. Some can be rather troublesome to install. You need a bit more effort to put in an undergravel filter, and you have to get this done while the fish tank doesn’t have water. Wet dry filters along with canister filters are also more suited for larger tanks, and consequently they’re generally more complicated to install. 

If you’re getting a filter, just make sure you can find an online video of how to install it. You can do make sure that you can put it in yourself with no trouble.

Water Flow Rate

The general rule of thumb for the water flow rate of your fish tank filter is that you turn over the entire volume of the tank 4 times each hour. So, if you have a 20-gallon aquarium, it’s common to have your pump and filter operate at a flow rate of about 80 gph (gallons per hour). That’s the best rate for biological and chemical filtration, though these filtration types can work with a slower flow rate. However, with mechanical filtration you really need a fast flow rate. 

However, aquarium size is just one of the considerations when you’re figuring out the proper water flow rate. The size of your fish will also be a factor here. If you have comparatively larger fish, you’ll need higher flow rates. The same is true if you have a reef tank, as the higher flow rate makes sure your water is moving through all the spots in the aquarium. 

You want slower water flow rates when you have smaller fish like bettas, and baby fish. The fast flow rate will just stress them out, since it takes a lot more effort to swim through the stronger current. A slow flow rate is also recommended if you have live plants in your tank. Lots of plants can’t really handle being right smack in the middle of a very strong current all the time. You also want to minimize the water agitation on the surface to make sure your water holds on to the CO2 your plants need to survive. 

Keep in mind that the stated flow rate for aquarium filters may not be entirely accurate. Usually, these rates are for optimal conditions, and you may not have those conditions all the time. Also, these are the flow rates when you’ve set your fish tank right on the floor. Lots of people raise their fish tanks off the floor by about 4 feet or so, and that altitude can lower the flow rate when the filter uses a low-powered pump to move the water.

Noise Level

Having an aquarium in a room can be a very relaxing and soothing fixture to help you relax. But this effect is marred when you have a noisy fish tank filter. The quieter it is, the better. 

Obviously, these things can’t be totally quiet. After all, in general they use pumps to move the water in the tank through the filtration system, and pumps make noise. Some of these filters, however, are comparatively silent and after a while you learn to ignore the slight sound they make.


Cheap filters are no good if their quality is also so cheap that they break down very quickly. It’s better to just spend a bit more for a filter system that lasts longer and on which you can rely to work effectively. You should check out the length of the warranty period to gauge how much confidence the brand has on the durability of their filter products. A quick look at customer reviews should also make it clear if too many of them are complaining about broken parts too soon after buying.

Aquarium Filter FAQs

Here are some answers to questions that most people ask about fish tank filters:

How do I really decide which type of filter is the best for my aquarium?

If you’re a relative newbie to the hobby, your best option is to go with the recommendation of an expert you trust. So ask at the pet store for what filter they think will work best for your aquarium. Go join online forums and ask around. When you read reviews, pay close attention to reviews written by people who own the same type and size of aquarium as you do, and who own the same types of fish. Their input can be very illuminating.

Is it true that you can do without a filter if you have a very small (nano) fish tank?

Technically, it’s possible to do without an aquarium filter when you have a nano aquarium. You will then just make sure you change about one-fifth of the water to keep it clean and the tank a healthy place for your fish. You’ll still need live plants for your tank, while you also need “eco-complete” gravel to keep these plants healthy. 

But most people aren’t complete shut-ins. What if you have to be away every so often? If that’s the case, a filter can help make sure that your fish are all still alive when you get back.

If I have a really effective fish tank filter, do I really need to replace the water all that often? 

There’s no such thing as a filter so completely effective that you won’t need to replace the water. You have to replace the water on schedule no matter what. Also, you will need to clean the aquarium itself every now and then. 

How often should I clean my aquarium filter?

When it becomes dirty, just clean it. After a while, you should notice that there’s a general period of time when it becomes dirty so you can clean it regularly on schedule.

What you don’t want to do is to delay cleaning the filter because you think that you can still get a few days or even a couple of weeks of use before you need to clean it. Doing this represents an unnecessary risk to the health of your fish. Just do instead.

Just how much waste does my fish produce?

That depends on your fish. You don’t really have much of a problem with fish excrement when you have small thin fish like neons, harlequins, and bettas. But other types of fish, like mollies, guppies, platys, and goldfish can real make a lot of mess in the water. If you have these types of fish, you better have a really effective fish tank filter.

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