Fluval FX6 Canister Filter Review – FX6 vs FX4 Who Wins!

Estimated read time 12 min read

The Fx6 fish filter is massive! It looks like someone took a shop vac and converted it into a canister filter; this filter is HUGE! The FX4 is big as well.


But before we get into the details of the review, here are just 3 of the key features these monsters offer.

Self-starting canister filter: Add water and plug it in. This canister filter system does all the work, eliminating the need to siphon water or prime the filter yourself.

Smart pump technology: Every 12 hours, the filter will stop, allow any trapped air to escape, and then restart. This ensures the best filtration efficiency at all times.

Seamless Water Changes: The FX6 & FX4 feature a utility valve at the unit’s base, which can empty the unit and complete your water changes by draining and refilling right from the valve.

In this review, we’ll talk about some key features that make this beast a top performer for the price point and one of the best canister filters on the market.

What are the seven best features of the Fluval FX6 & FX4?

  • The self-starting feature adds water and plugs it in. The filter primes and starts itself. 
  • The filter media baskets easily lift out for cleaning with “tote handles” that pull out.
  • Energy-efficient motor assembly uses 10% less power than previous models.
  • Quickly do water changes and clean your gravel: attach a hose to the utility valve located at the base, and the filter does the rest. You can store the extra hosing with the easy storage clips on the canister lid when you are done. Check out the video below for a demonstration.
  • Prevent leaks with large locking clamps that secure the motor and canister.
  • Every 12 hours, the filter will stop, allow any trapped air to escape, and then restart. Regular aquarium water filtration ensures optimal results.
  • Don’t worry about problems. It came with a three-year warranty and was built with heavy-duty construction.

What is the best feature of the Fluval FX6? 

The ability to attach the all-new Fluval FX Gravel Vac (compatible with FX4, FX5, and FX6 model filters) offers powered and convenient substrate cleaning for your aquarium.

Watch this video showing how the FX6 simplifies cleaning your gravel.

From Fluval Aquatics

Quick Overview Of The Fluval FX6 & FX4 Canister Filters


  • The massive Fluval FX6 canister filter is a multi-stage filter that is good for fresh and saltwater aquariums up to 1500 L (400 US Gal).
  • One of the great features of the FX6 is its highly efficient motor which consumes 10% less power than the FX5.
  • The FX6 brings back the smart pump technology from the FX5 models, which stops the filter every 12 hours to maintain optimal fish tank filter performance.
  • The intake tube is telescopic, so you can adjust the length to suit whatever size gallon tank, and it also features an anti-clog strainer to keep the water flowing.
  • Everything from the valves, media tray, intake/outtake tubes, and the canister is well-built and super durable.


  • Only a few changes from the FX5. But it isn’t easy to improve much on an already brilliant filter.
  • The size of these units means you need a big place to store them. However, considering these beasts’ filtration capacity, it’s worth the trade-off.

First, the FX6 is a fantastic filter, but if you already have an FX5, there is no need to upgrade.

The main changes are color aesthetics and the fasteners used to be rubber.

However, if you are looking for a new filter and the price for the FX5 & FX6 is within the same range, I suggest you go with the FX6.

I think it’s the best canister filter made right now; if you have the money and want a filter that does everything itself, then the FX6 is the way to go.

Is the Fluval FX6 quiet?

Being one of the largest canister filters with a massive pump, the Fluval FX6 is very quiet. However, as with most filters and powered equipment, a low humming is only detected when close to the aquarium.

Seamless Water Changes

Aquarium system filtration maintenance is essential for maintaining a healthy aquarium. Recently, Fluval updated their FX6 & FX4 tanks with a built-in water change system, multiple filters, and even an optional powered FX gravel vacuum with independent filtering capability.

Check out this video showing all the new features of the Fluval FX6 & FX4

From Fluval Aquatics

What Comes With The Fluval FX6 & FX4 – What’s In the Box?

So What Comes With The Fluval FX6 & FX4? Well, to be honest, everything!

It includes all the pipework, attachments, and all the filter media you need to plug it in and watch the filter do the rest.

The Fluval FX6 & FX4 come with a 3-year manufacturer’s warranty.

Here’s the list;

  • Ribbed Hosing
  • Rim Connectors
  • Strainer
  • Output Nozzle
  • AquaStop Valves
  • Canister
  • Utility Valve Housing
  • Power cord for the pump unit
  • Media Baskets
  • Filter Lid & Accessories

Included Media:

  • Foam
  • Bio Foam
  • Biomax Ceramic Rings
  • Carbon Pad
  • Media Bags

You can also check out this Fluval FX6 unboxing by Stuff & Us. Then continue reading below to see how to set up this filter.

This is the most accessible canister filter I have ever set up.

As soon as you plug the filter in, the canister fills with water from your aquarium.

It pumps for 1 minute, pauses for 2 minutes to evacuate air from the system, then immediately begins the filtering process.

Check out this video from Big Al’s, where they go over some of the key features but then show you how easy it is to set up this beast of a canister filter.

Fluval fx6 media setup:

The Fluval FX6 comes with all the media you will need to run the filter; refer to the product list above for all the media included.

The FX6 comes with three huge media trays, which all have circular sponges around the perimeter from top to bottom, around 2″ thick. The FX4, to contrast, has only two trays.

Here are two cross-sections of both filters so you can see how the media stacks up when comparing the two filters.

It’s also important to note that Fluval has provided a Basket in Basket media tray design which effectively allows you to provide up to 6 stages of filtration for the FX6 and five stages of filtration for the FX4.

Here is a breakdown of each tray and the six filtration stages possible with the FX6 aquarium filter;

Top Media Tray #1

  1. Bio Foam
  2. Bio Foam
  3. Foam

Middle Media Tray #2

  1. Bio-Max Rings
  2. Bio-Max Rings
  3. Foam

Bottom Media Tray #3

  1. Carbon Pad
  2. Foam

This may look like eight stages, but the Foam is counted as one stage as it sits in the outer ring of each tray and, when stacked (See the pictures above), forms one continuous stage of mechanical filtration.

Here is a suggested setup for the trays that could work well.

However, constantly research to ensure the media you use will protect your fish.

  • First tray: Clearmax and Purigen
  • Second tray: Pond matrix
  • Third tray: Chemi pure
  • Bottom: Filtering pad for polishing, same on top.

Tip: To get your water clear, use Poly-Fil. Make sure that it’s 100% polyester. You can get this stuff cheap on amazon. Then surround your media with this stuff. Finally, lay it on top as well.

The Fluval FX6 gets excellent ratings in all categories and all stores; it may seem perfect. Still, it has some problems, so we compiled a considerable troubleshooting guide to fixing the most common Fluval FX6 issues.

Check out some of the ratings below.

You can feel confident that you are picking a winner, whether buying your first canister filter or having been around the block a few times.

Further Reading: Need Help Finding A Canister Filter? Our Guide Can Help You Find The Best Canister Filter For Your Aquarium And Your Needs. We’ve Reviewed All The Top Brands From Fluval, Ehiem, API, Marineland, And More.

Frequently Asked Questions:

How long does a Fluval FX6 last?

The Fluval FX6 is known for its longevity and is not uncommon to last over seven years. It also comes with a 3-year warranty for added peace of mind. So when investing in a Fluval FX6, you can be sure that you are getting a filter that will last for a long time.

What size tank is an FX6 good for?

The Fluval FX6 canister filter is suitable for large fish tanks of up to 400 gallons, with a filter circulation rate of 563 GPH and a filtration volume of 5.28 gallons. It is also perfect for smaller setups with advanced filtration needs, such as predatory fish or turtle setups, and can be used in aquariums as small as 55 gallons. In addition, it uses 10% less energy than its predecessor models, making it an energy-efficient option.

Are Fluval canister filters good?

Generally speaking, yes. The Fluval FX6 is an excellent option for large tanks that need powerful filtration. Its efficient motor and large interior for customizable media makes it the perfect choice for tanks up to 400 US Gal. In addition, the telescopic intake tube and anti-clog strainer increase the filter’s convenience and reliability. For smaller tanks and setups with advanced filtration needs, the Fluval FX6 may be overkill. However, if you’re looking for a robust, reliable, and easy-to-maintain filter, the Fluval FX6 is one of the best choices on the market.

What is the actual flow rate of Fluval FX6?

The actual flow rate of the Fluval FX6, based on the numbers on the packaging, is estimated to be 563 GPH. The water pressure exerted when the canister filter is used is the pump speed and GPH.

How difficult was it to get this filter set up?

Setting up the Fluval FX6 filter could be pretty challenging due to the extensive instruction manual and the complexity of the hoses. It can take up to two hours to get the filter properly set up, and the hoses can be difficult to fit into the holders. Maintenance, however, is relatively easy thanks to the drain at the bottom of the filter, allowing easy water removal.

What does the Fluval fx6 offer?

Setting up the Fluval FX6 filter could be pretty challenging due to the extensive instruction manual and the complexity of the hoses. It can take up to two hours to get the filter properly set up, and the hoses can be difficult to fit into the holders. Maintenance, however, is relatively easy thanks to the drain at the bottom of the filter, which allows for easy water removal.

How often do you change the charcoal in a canister filter?

How often do you change the charcoal in a canister filter? Generally, it is recommended to change the charcoal filter media in a canister filter every 2-4 weeks. However, this may vary depending on the filter you are using, the size of your tank, and the bioload of your tank. For example, if you use the Fluval FX6 in a small 50-gallon tank, you may only need to change the charcoal filter media every six months. On the other hand, if you are using the Fluval FX4, a smaller filter in a high bio load 500-gallon tank, monthly charcoal filter media changes may be necessary. Additionally, if you are using carbon media, changing the filter media every month is recommended.

How well does this filter maintain water parameters?

The reviews for this filter suggest that it is highly effective at maintaining clean water in aquariums. One reviewer stated that the water remained pure and clean for over two months and that the filter was a snap to clean. Another reviewer mentioned the powerful water movement and the fact that the filter was very quiet. With regular water changes, this filter can go about 4-5 weeks before needing to be cleaned. Overall, it does an excellent job of maintaining water parameters

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