The Fluval 406 – A Closer Look

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Are you considering the Fluval 406 Canister Filter for your tank?

One of the most important considerations when setting up a fish tank is water filtration. A water filter is one item you don’t want to skimp on especially if you have a larger tank. 

Serious aquarium owners know that the best type of filters on the market are external canister filters and the Fluval 406 certainly fits that bill.

This is a popular and commonly recommended filter. But does it live up to the hype? How does it compare to other canister filters? Is it worth the price? Continue reading below and I will dive into all of the nitty-gritty on the Fluval 406.

Is The Fluval 406 The Right Filter For You?

While I personally believe the 406 is a great filter it isn’t the best fit for all applications. There are some basic things you need to consider before choosing a filter. 

What Flow Rate Do I Need? 

Aquarium filter output is measured in Gallons Per Hour or GPH. This is the measure of how much water a filter moves through tank in an hour. 

It is important to match your aquarium size to the proper GPH rated filter. Not enough flow and your water will quickly be contaminated with fish detritus and other contaminants.

On the high end you want to aim for a filter that will turn over the volume of your aquarium 4 times in 1 hour. For example, if you have a 30 gallon tank (114 liters) you want a flow rate of up to 120 GPH (456 LPH).  This is a general rule of thumb and some filters are more efficient than others. With an efficient high quality filter you may be able to get by with less.

How Much Room Do I Need for Filter Media?

There are a wide variety of filter media on the market today. Many people have their own preferences and mixes they prefer such as pumice for biological filtration, resin for chemical filtration, etc. 

The more space and compartments a filter has the more options you will have. So pay attention to filter specifications such as media capacity and number of media trays. 

Are Replacement Parts and Media Easy to Find?

There are a variety of brands available on the market. Many of these are knock offs or off-brands. These off brand filters likely don’t have replacement parts available and the customer service will be poor or non-existent. 

For these reasons it’s usually best to go with an established brand that has good customer support. 

Fluval 406 Canister Filter Review

Fluval is an established brand leader in the aquarium space. They launched their first filter all the way back in 1975. This filter was revolutionary in that it was the world’s first 3 stage filter. It’s clear they know a thing or two about designing a quality filter. Of their offerings, the 406 external canister filter is a popular choice for many reasons. 

The 06 line of Fluval external canister filters includes the 106, 206, 306, and the 406. The 406 is the largest filter in this line of filters and is recommended for tanks up to 100 gallons (400 liters). This 06 line is an improvement over its predecessors, the 05 line of filters. It boasts easier setup, cleaning, priming and overall better performance. 

Let’s take a look at a broad overview of the pros and cons of this filter. 


  • Quiet operation
  • High pump output 383 GPH (1450 LPH)
  • Easy to clean
  • Well built by a reputable company
  • Large media capacity 2.2 gallons (8.5 L)


  • May develop impeller issues (3 year warranty)
  • No spray bar included
  • Can leak if not sealed correctly

Fluval 406 Features And Specs

Look And Design

Overall this seems to to be a sleek, well built canister filter. The dimensions are 10 X 8 X 20 in. (25 X 20 X 50.8 cm) which gives it a square shape rather than round like some canister filters. This gives it a more compact design that fits more neatly into an aquarium cabinet or other space. 

It is constructed primarily of heavy duty plastic and has a solid feel. The only negative I see with the design are the ribbed tubes with the white connectors. While the ribbed design helps the tubing flex and bend, it seems rather cheap and can make them hard to clean. Additionally, the white hose connectors look out of place on a nearly all black unit. 

383 GPH Flow Rate

The pump in this filter is capable of moving up to 383 gallons (1450 liters) of water per hour (GPH). This means that this external canister filter is sufficient to filter an aquarium of up to 100 gallons (400 liters) in size. 

Of course this depends somewhat on stocking levels. If you remember from above we want to aim for a water turnover rate of 4:1 GPH to tank size. Since 383 GPH is just below our 4:1 turnover rate I wouldn’t recommend this filter for an overstocked 100 gallon tank. Moreover, with hoses connected and filter installed the flow rate is closer to 245 GPH (930 LPH). Don’t let this worry you though as this unit is very efficient at filtering water. A reasonably stocked 100 gallon tank would be just fine.

With such a powerful flow rate this can create a strong current in your tank. This may be a positive thing for some aquariums. Crinoids, bamboo shrimp and other filter feeding organisms will benefit from the current and more easily filter out suspended particles.  

While the strong current may benefit certain aquatic organisms and fish, it’s too strong for others. There is an adjustment valve to control the flow rate but this will also cut down on the filtration rate. The best way to reduce this current is with a spray bar. Unfortunately, this unit doesn’t come with a spray bar so it will need to be purchased separately. 

The filter intake flow may also pose a problem for small delicate fish. I recommend a sponge pre-filter or larger fish guard to prevent them from being sucked into the intake tube. 

Large Internal Media Capacity

The media within a filter is responsible  for the actual water filtration. This is why using media that effectively tackles mechanical, biological, and chemical filtration is so important. The Fluval 406 external canister filter performs these functions with ease. 

Unlike some external canister filters which are round this one has a square shape. This shape gives the canister a 30-50% higher water capacity than similar sized round canisters. This means that it will also hold more media which will aid with more complete filtration. Thus, the Fluval 406 has a generous media capacity of 2.2 gallons (8.5 liters)

This canister has 4 removable media trays with included media to get you started. Of course there is a lot of room to customize your own personal media blend if you so choose. Built into this 4 tray design is a complex water flow path that maximizes contact with this media. 

Self Priming

The Fluval 406 includes a self primer which is designed to make priming a breeze. To prime you have to simply pull up and push down the priming handle 3-4 times. While this works like a charm for some, others seem to have a lot of trouble priming this filter. 

Some of the difficulty with priming is likely due to improper setup. Loose connectors, bad o ring seals, and improper filter placement are likely contributing factors. So take care to set up the filter properly. 

If you still struggle with priming this unit the video below has another priming method that is sure to help. 

Whats Included With The 406?

  • 4 x foam pads
  • 4 x 70 g carbon
  • 2 x polishing pads
  • 2 x 120 g BioMax
  • 2 x Bio-FoamAquaStop valve assembly
  • Ribbed hosing
  • 2 rim connectors
  • Intake tube
  • Intake strainer
  • Output nozzle
  • 2 rubber connectors
  • Instruction manual
  • Quick start manual

Fluval 406 Setup And Maintenance


Care must be taken to set up this filter correctly to prevent problems and ensure efficient operation. Incorrect setup can result in water leaks, priming issues, noisy operation, and premature failure of the filter. 

The instruction manual is easy to understand for most and includes good illustrations. Take care to read the instructions and follow them as directed. 

In addition to the setup steps included in the instruction manual some additional setup tips include:

  • Cut the hose that returns water to the tank (output) shorter than the hose that pulls water from the tank (intake). This will help make the motor run more efficiently and almost silent.
  • Lube the o-rings with aquarium safe silicone grease! One of the main problems with this filter is that many people report leaks. Lubrication will help create a more effective seal.


Cleaning the Fluval 406 is an easy, straight forward process. You simply flip up the aquastop valve (prevents the lines from draining), detach the hose connector block, and pop the top of the filter off. 

Once open, you can remove the media trays and clean just as you would with any other filter. This process can take as little as 10-15 minutes.

Final Thoughts

While some people seem to have problems with leaks and priming, these issues can be mitigated with proper setup. Likewise, the impeller issues experienced by a few are covered by Fluvals 3-year warranty. In short, I wouldn’t let these few negatives deter you into buying this filter. 

Overall I think the Fluval 406 external canister filter is a solid unit. It is built by a long standing reputable company, is well built, has high output, and has some great features. These facts are reflected by the popularity of this filter. 

If you like this filter but aren’t quiet convinced check out the Fluval 407 instead!