Fluval FX6 and FX4 Reviews – High Performance Canister Filters

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Looking for a powerful canister filter for your Aquarium, Fluval FX series Canister Filter is definitely the one for you. Made with precision and an objective of providing the best, the Fluval FX6 and the FX4 are the Beast.

Today we have reviewed Fluval FX6 Aquarium Canister Filter and Fluval FX4 Aquarium Canister Filter, read on to know more about them.

High Performance Delivered

With a multi-stage filtration unit and a powerful motor unit, the filter provides promising results. You will be amazed by the clarity of the water, post filtration. While our Fluval FX6 review for a 350-gallon aquarium the filter was able to clean the tanks murky water, eliminating even the tiniest contaminant.

Fluval FX6 Price and Fluval FX4 Price

Fluval has designed the FX6 and the FX4 to accommodate more filtration media using less space. Fluval FX6 has 6 media compartments, while the FX4 has 5 media compartments making enough room for the media. And with a variety of stock media that comes with the filter, you do not have to get additional media. You can have Fluval Fx4/FX6 media setup as displayed in the figure below.

Filtration Stages of Fluval FX6 and Fluval Fx4

Figure 1: Filtration Stages of Fluval FX6 and Fluval Fx4

Fluval FX6 and FX4 Filter Setup

You don’t have to be worried about the filter setup, rest assured the filter setup is quite easy. The steps for Fluval FX6 and Fluval FX4 media setup are almost similar and quick.

Here’s how you can quickly set up your Fluval FX series filter in 5 quick steps:

  1. Unpack the media and wash them before use, and place them in the media basket.
  2. Fix the media baskets with the T-Bar and place it in the Canister.
  3. Close the lid after adding water in the Canister. (Adding water is to help in Priming the filter) and secure it with Easy grip locking system.
  4. Connect the input and the output tubes to the filter. If required, cut the inlets and outlet connectors to the required length.
  5. Attach the intake strainer and output nozzles, place them in the Aquarium using the suction cups.

And the setup is done!!! Switch on the Filter and you good to go.

Priming the Filter

Fluval has ensured that the priming remains effortless and less of a nightmare.

Wondering How?

With a smart pump technology, the Filter takes care of the priming by itself. Just add water to the Filter while closing the lid and start the Filter. That’s everything required for starting the filter !!!

The Filter would start, then run for approximately 2 minutes and shut down automatically remove air bubbles and then automatically restart.

Filter Operations

Fluval FX6 Maintenance

Fluval FX6 Maintenance Dials

While it comes to operations, the FX series filters are extremely quiet while running. Quite Operations –  But that’s almost all the good filters in the market tend to have, don’t they?

What’s so unique about the Fluval FX series filters?

The Fluval FX6 and FX4 have the precise-engineered bearing installed that ensures you do not hear even a slightest of hmm.

And what about the Bypass and Leakage?

With the Leak Proof design of the media basket, leakage is avoided ensuring there is no bypass.

 Fluval FX series filter could be used for Freshwater and Saltwater Aquariums 

Smart PumpTM

The Fluval FX6 and FX4 comes with an advanced microchip technology called as Smart PumpTM that continuously monitors and optimizes pump performance. Smart PumpTM maintains the Impeller Speed and the Pump Power ensuring optimal flow rate throughout.  Also, the Smart PumpTM checks for trapped air and is evacuated if any, every 12 hours. This makes the filter Energy Efficient, for running at maximum power only when required.

To protect the filter from damage, a safety feature is included that would turn off the motor whenever impeller is impeded.


Fluval Fx6 and Fluval FX4 Review and Specifications

Fluval FX6 Review

For our Fluval FX6 review, we installed Fluval FX6 External Canister Filter to a 350 US Gallon tank. The tank water was cloudy with added impurities and bio-waste to test the actual filtration efficiency of the filter. The filter did an exceptional job in cleaning the impurities and other waste making the water crystal clear.

Though with the added impurities and water being very cloudy the filtration time was more than normal. But later in the week filtration was carried out normally.  As Figure 1 indicated, the filter has 6 filtration stages to ensure optimal filtration of your tank. Read the specification to know what’s included in the box.

Fluval FX6 Specs:

Sr. No.SpecificationDetails
1CapacityFor fresh and saltwater aquariums up to 1500 L (400 US Gal)
2Flow Rate563 US GAL
3Pump Output(925 US G/H)
4Wattage120V/60HZ – 43 W AND 230-240V/50HZ – 41 W
5Media Baskets6
6Media IncludedFoam Filter Pads, Bio-Foam Pad and Bio Rings(Biomax).

Fluval FX4 Review

For our Fluval FX4 review, we installed Fluval FX4 External Canister Filter to a 200 US Gallon tank. But unlike our Fluval FX6 review we had installed the filter in a live aquarium setup an here are the results of testing it for about a month. The filter works just great!!! Spotlessly cleaning your tank and that too without making any noise.

Fluval FX4 has 5 filtration stages and comes with all the media to get started. You can use additional media if your tank requires some. Also as described above we had no problem in setting up the filter nor with starting up. For more details refer the table below.

Fluval FX4 Specs:

Sr. No.SpecificationDetails
1CapacityFor fresh and saltwater aquariums up to 250 US GAL
2Flow Rate450 Gal/h
3Pump Output700 US GAL/h
4Wattage120V/60Hz: 30 W and 230-240V/50Hz: 30 W
5Media Baskets5
6Media IncludedFoam Filter Pads, Bio-Foam Pad and Bio Rings(Biomax).

Here’s a video on Fluval FX6 setup by Fluval Aquatics. The video also covers an overview of the filter as described above.

Check out the Best Canister Filters reviewed by our experts.

Fluval FX6 vs FX4

Here’s a summary of Fluval FX6 vs Fluval FX4

FeatureFluval FX6Fluval FX4
Flow RateUp to 925 gallons per hour (GPH)Up to 700 GPH
Tank SizeSuitable for aquariums up to 400 gallonsSuitable for aquariums up to 250 gallons
Media Capacity5.9 liters (1.5 gallons)3.7 liters (1 gallon)
Filtration Stages6 stages (Mechanical, Chemical, Biological)5 stages (Mechanical, Chemical, Biological)
Smart Pump TechnologyYesYes
Aquastop ValveYesYes
Self-Priming SystemYesYes
Built-in MicrochipYesYes
Maintenance IndicatorYesYes
Filter Volume20 liters (5.28 gallons)14 liters (3.7 gallons)
Height17 inches (43 cm)15 inches (38 cm)
Width15 inches (38 cm)15 inches (38 cm)
Weight19.6 lbs (8.9 kg)14.5 lbs (6.6 kg)
Warranty3 years3 years
Fluval FX6 vs Fluval FX4 canister filter comparision

Both the Fluval FX6 and FX4 are powerful canister filters designed for large aquariums. The FX6, being the larger model, offers a higher flow rate and greater media capacity, making it suitable for larger tanks. However, the choice between the two depends on the specific needs of your aquarium and the size of the tank you are maintaining.


So, how is Fluval Fx6  and FX4 different from the rest in Terms of Maintenance?

The flow rate of the filter is very good and maintained till the end of the maintenance cycle. Since the water passes through the outer foam first, larger debris is eliminated maintaining the flow rate and preventing clogging of inner media.

The filter comes with a lot of handy functions that makes the maintenance hassle free just like setting up the filter. Many times we tend to forget the maintenance schedule, so the filter comes with the Indicator Dials so you never miss the next maintenance and water change date.

And there’s more…

Additionally the purge valve at the bottom of the filter that could assist you in avoiding a mess while carrying out maintenance.

The Purge Valve

fluval fx4 water change

Utility Valve at the bottom of the filter

The Fluval FX series Filter comes with a unique feature of ‘Purge valve‘ also called as the ‘Utility valve‘ which comes in handy to avoid a mess.

It is a multi-purpose valve at the bottom of the Filter which could be used as a direct input or output. The Gravel Vac cleaning uses utility valve for the input, whereas you could empty the tank or refill it using the utility valve.

 Helps you empty the canister before moving it for maintenance. 

You could do empty/fill your tank using the utility valve, avoiding the mess caused by manual siphoning.

Here’s How:

  • Turn off the input and the output AquaStop valve
  • Attach a hose to utility valve with an output to the bucket or to drain.
  • Turn on the input aqua-stop valve and the utility valve.

And similarly, you could fill in the tank using the. We found this approach quite convenient since there was hardly any water spillage and mess. And we are sure you would love it too.

And there’s even more…

fluval fx4 review/fluval fx6 review


Gravel Vac

powered fx gravel vac

Fluval FX series Gravel Vac

The Gravel Vac(Included in the newer models) is a unique add-on feature which is very useful for cleaning the parts of the Aquarium which are not reachable during normal filtration. Using an extended suction pipe, prefiltered and then let in through the utility valve. The water sucked in then goes through the filter media in the media baskets and finally clean water is back through the Filter outlets.

This a feature that you would find very helpful in maintaining the overall health of the Aquarium by eliminating plant debris, excess food, fish waste and much more. The fine filter pad is capable of cleaning even the finest of particle leaving you tank sparkling clean. This is a unique feature among the filters in this range.

Here’s a video by Fluval Aquatics demonstrating Fluval FX Canister Filter Gravel Vac in action.


With loads of features included, Fluval has thoughtfully designed this filter to provide a hassle-free user experience making it a preferred choice. We would recommend Fluval FX4 and Fluval FX6 if you are looking for a Canister filter for aquariums in a range of 400 US Gallons.

Fluval Fx6 and Fluval FX4 Review
  • Mode of Operation
  • Maintenance
  • Filtration Efficiency
  • Features


Both Fluval FX6 and FX4 delivers exceptional performance, also comes with hand features for easy maintenance. With an incredible build quality and silent operations it a Power Packed Canister Filter.

Follow Bryan:

Bryan, a seasoned aquarium hobbyist, boasts over a decade of dedicated fishkeeping experience. His passion for aquatic life has cultivated a wealth of knowledge, making him a go-to expert in creating thriving and balanced underwater ecosystems. From vibrant fish communities to lush planted tanks, Bryan's journey is a testament to the rewarding art of aquarium care.

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