Our 2023 Fluval FX6 Canister Filter Review: What A Beast!

The Fluval FX6 is the cream of the crop when it comes to canister filters. Plain and simple.

It’s on the shortlist for best canister filters on the market when you talk to any fishkeeper who’s been in the game long enough. In fact, it’s really built up quite the reputation for itself!

So if you don’t feel like reading a full review and want to skip to the spoilers, here’s the gist of it:

You’ll be very happy with the FX6 if you’re thinking about picking up a new canister filter.

However, if you want to get into the nitty-gritty details and learn about everything from specs to setup, we’ve got you covered.

We spent a significant amount of time researching and testing the Fluval FX6 canister filter so we could share the results with potential buyers like you.

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Let’s get started.

Product summary

Fluval has been churning out high-quality products for a very long time now, and the FX6 canister filter is no exception.

Whenever you have products that are built by such a reputable company, that gives you a reason to feel confident right off the bat.

Actually, it’s little brother the FX4 was the very first solo-product review we published on this site!

And our Fluval FX6 canister filter review will be the second.

The reason for this is simple. The Fluval FX6 just does a fantastic job.

Fluval FX6 Canister Filter

  • Multi-Stage Filter that produces healthy aquarium water, freshwater or marine aquariums
  • Features Smart Pump Technology for optimal filter performance, efficiency and management
  • Self-starting filter: just add water and plug in
  • For aquariums up to 400 gallons

It’s capable of filtering an extremely large amount of water very effectively. We’re talking tanks up to 400 gallons!

It’s probably the most popular and well-respected filtration systems among aquarists with large tanks. It over-delivers and gives you the reliability that you would expect from the Fluval brand.

But here’s where it gets crazy:

The FX6 is tiny!

With this product, you get a canister filter that can handle a massive amount of water, boasts an impressive flow rate, and doesn’t require a lot of maintenance.

And the dimensions are 15 x 15 x 20 inches.

This means you can tuck it out of the way in pretty much any tank setup while still getting a very impressive filter performance.

That makes it a winner in our book.

Specs & details

To give you a high-level understanding of the Fluval FX6 canister filter, here are some quick specs that will help you during the shopping process. In the sections below we’ll cover these in more detail.

  • Pump output of 925 gallons
  • It weighs 19.9 pounds
  • Media baskets hold 5.9 liters
  • The dimensions are 15 x 15 x 20 inches
  • Can be used in freshwater and saltwater aquariums
  • Works for tanks up to 400 gallons
  • Self-starting filter for easy setup 
  • Usable with any kind of filter media

FX6 dimensions

The dimensions of the Fluval FX6 canister filter are 15 x 15 x 20 inches, with it weighing in at 19.9 pounds. This might seem a little big if you’re not used to high output aquarium filters, but it’s really not.

The dimensions give you the option to tuck it away under your tank without having to change your setup or make additional room. Space management is critical when you’re in the larger tank game, so this makes a big difference.

True GPH

There has been some confusion in the aquarium community about the true GPH of the FX6. That comes from a slight disconnect between the numbers you see on the box, and the practical in-use GPH when you have everything set up.

The output that is advertised is 925 GPH. However, you have to think about canister filters in use and the pressure that impacts pump speed. When you do this the more accurate number to keep in mind is 563 GPH.

Build quality

The overall build quality of the FX6 is stellar. When you get your hands on it you can just tell it does the job.

It comes with some very effective aqua stop valves which make using the filter a breeze. You can easily stop the water flow without having to risk damage or and stray water escaping one of the components.

This is one thing that a lot of canister filters get wrong. They come with a stop valve, but if you end up using it there is a price to pay.

The FX6 also comes with a sophisticated circuit which ensures that everything is running exactly as it should. This will help give you peace of mind when away from your fish tank.

It runs constantly and we’ve heard many reports that you can rely on and trust the monitoring system that comes with the filter. This is a testament to the overall quality of the components that Fluval puts in their products.

You also have the ability to adjust and tweak the output via the dual output nozzles that are found on the top of the canister filter. This is something you will likely be playing around with at first, so this will save you time and make this process a little easier.


You would think that with the impressive output that the Fluval FX6 canister filter brings to the table there would be some additional noise right?


In fact, it’s one of the quietest canister filters on the market today! You can have this in any part of your house without having to worry about the noise causing a disturbance.

This is primarily due to the internal components being high-quality and well-designed. The rubber feet that help muffle vibrations help too.

Noice is one of the most overlooked factors to aquarium products, but we place a premium on the ability for gear to run quietly.

The FX6 filter passes this test without a doubt.

Intake strainer

When you get the FX6 you also get a very solid intake strainer that will significantly reduce the chance of your filter clogging. When you’re dealing with such a high GPH, this is a big difference-maker.

If you do end up needing to get in there and do some cleaning due to clogs or maintenance issues, there’s an easy to use purge valve on the bottom. Purge valves are a necessity for canister filters and can make water changes easy, but some of them are a pain to use. Fluval designed theirs perfectly and we think a handful of other manufacturers could learn a thing or two from the subtleties of their design.

Media baskets

In our Fluval FX6 canister filter review, we wanted to spend an appropriate amount of time on the media baskets. This is something that owners get a lot of use out of, so it was worth a close look.

With the FX6 you get three baskets that hold an impressive 5.9 liters. This amount helps keep things convenient and easy since you can drop in a large amount of filter media.

The quantity of media baskets is also another plus. With some canister filters, you have to pick and choose when it comes to the media you add to your tank. The FX6 gives you the ability to try any combination you want.

Despite the large capacity, it’s really easy to remove the media baskets and change them out. There’s a release handle that quickly gets you into the tray area where you can grab whichever basket you need. If you have your media handy you can make a full change in minutes.

If you’re an aquarist who is looking for an impressive amount of media capacity, this is the choice for you.

The visual appeal

While this might not be a priority for everyone, it’s something that we want to take a second to talk about. For many aquarists, the design and aesthetic appeal of the gear they purchase plays a part in how they go through the buying process.

In our opinion, the Fluval FX6 is a beautiful looking product that won’t be an eyesore if you decide to keep it out in the open.

The combination of red, white, and black colors is a classic that looks great without being over the top. It’s very similar to the FX4 in that regard, which we hold in very high esteem visually.

If you were impressed by the capabilities of the FX6 then you might not care about the design one way or the other, but if you had to choose you might as well go with the pretty option!


One of the things that many people worry about when it comes to canister filters is the setup and installation process. Thankfully, that’s not something you’ll have to think about too much with the FX6.

Right out of the box you have the self-priming feature which saves you from having to do any hands-on manual siphoning to get things started. All you need to do is add some water, plug it in, and you’re off to the races.

It’s this initial setup process that seems to be the scariest for new owners of all experience levels.

And we get it.

You just made an investment into a product that you want to get value out of. How awful would it be to mess something up and break it on day 1?

Besides the raw performance and reliability that you get with the FX6, we heavily considered ease of use into our review. The setup process is a perfect example of how this product shines in that regard.

Once you have everything up and running it becomes a process of tweaking the settings to get everything working how you need. You can adjust the intake, output nozzles, media, and more. 

You’ll have everything you need to get started as well. This isn’t one of those deals where you have to buy a bunch of other crucial components separately. 

The Pros And Cons

Overall you can probably tell that our Fluval FX6 canister filter review is overwhelmingly positive. However, that doesn’t mean this product is perfect.

Here are the pros and cons all listed out so you can see things from a birds-eye view.

The Pros:

  • Very reliable and easy to maintain
  • Filter media baskets are easy to access and give you options
  • Tremendous performance even with very large tanks
  • Makes very little noise despite the high power
  • Relatively small for the strength and output
  • A smart monitoring system that tracks impeller speed
  • Smart pump technology

The Cons:

  • Can take tweaking to ensure you don’t go overboard with the flow rate
  • Not a budget buy
  • Some lid removal issues just like its little brother (the FX4)
  • The tubing it comes with could be higher quality in our opinion

Our Conclusion

If you’re looking for an effective and high-performance canister filter for large tanks, the Fluval FX6 is the way to go.

Fluval FX6 Canister Filter

  • Multi-Stage Filter that produces healthy aquarium water, freshwater or marine aquariums
  • Features Smart Pump Technology for optimal filter performance, efficiency and management
  • Self-starting filter: just add water and plug in
  • For aquariums up to 400 gallons

It can handle large tanks with ease and does so in a way that removes headaches and hassles. This is a winning combination that has made Fluval a major player in the aquarium scene, and they backed it up yet again with this product.

We hope you enjoyed our review of the FX6 and highly encourage you to pick it up from Amazon.

You won’t be disappointed.

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