InTank Chamber 1 Media Basket for Fluval EVO 13.5 Review

The InTank Camber 1 Media Basket for the Fluval EVO 13.5 is a product that I didn’t want to love – that I resisted purchasing, and that I thought wouldn’t be a recommended tank accessory.   One reason behind this is my goal of saving money on our (mine and other’s) saltwater nano.

At the end of several years of use with this product, there is no more resistance.  I consider the InTank Media Basket for the Fluval EVO a must-have accessory (or as close to ‘must have’ as you can get). 

This filter media caddy won’t work for everyone’s needs, but I bet it will work for most setups.  I’ll discuss what this media basket does, its specs and features, and will report my experiences (both good and bad). 

InTank Chamber 1 Media Basket

Description and Specs for the InTank Chamber 1 Media Basket:

In short, InTank offers an aftermarket solution for holding filter media for various All-In-One aquariums like Fluval’s EVO 13.5. These media caddies are not only an improvement from stock, but in the case of the EVO 13.5, it solves some inherent design flaws of the tank. 

Overcoming Fluval’s Design Flaws with the EVO 13.5

I cover these issues in my review of the EVO 13.5, but Fluval intends for the first (of two) filter chambers to be allocated for an (optional) skimmer.  Chamber two houses there provided filter media (a sponge block, a bag of activated carbon, and a bag of ceramic rings). Chamber three houses the pump. (the diagram below is the stock filter media arrangement from Fluval – click to enlarge.)

the filter section of the Fluval EVO 13.5 saltwater aquarium

Issue number one is the stock filter media is not good.  The ceramic rings and carbon aren’t bad, but the filter block that they are housed in will become clogged up with detritus and nitrate-producing gunk over time.

Issue number two is that, for those of us who are not going to use a skimmer (in Chamber #1), the ideal place for filter media is at the top of Chamber #1.  It makes the most sense to place your filter floss (or a similar mechanical filter media) right where water enters the filter sections.  This way, the big stuff is removed and it keeps all the other chambers (and your remaining filter media) clean.

Even if you could have a means to place filter floss at the top of Chamber #1, this brings up the next problem – water flows sideways through slots midway down the wall separating Chambers 1 and 2.   It would make better use of the chambers if water flowed the full length (top to bottom).

The final problem is the bypass slot that Fluval places midway down the tank between the display section and Chamber #2.

InTank to the Rescue – Media Caddy Flow Characteristics:

InTank’s Chamber 1 Media Caddy solves or improves on all of these shortfalls. It’s a simple product but practically required for this saltwater nano.

InTank Chamber 1 Media Basket with overflow insert

The caddy is made of high-quality acrylic and slides down into the space of Chamber #1.  It features three perforated green shelves to hold filter media but allow water to flow through.

InTank Chamber 1 Media Basket for Fluval EVO 13.5 loaded with filter media

The most impactful of these shelves is the top one – it is perfectly situated high and directly in the cascading flow through the overflow slots (of the tank) and across the overflow insert.

The middle shelf is useful for any remaining filter media.  Water flows down and to the side to exit through Fluval’s dictated path (through the slots).  InTank makes this better by covering 7 of the 10 uppermost slots to force water through down through the media (on shelves one and two).  This middle shelf is removable.

removable shelf in the InTank Chamber 1 Media Basket for Fluval EVO 13.5

The bottom shelf, because of the fault in Fluval’s design, is not as useful because the water down at that level is more stagnant.  You can place media down there but it won’t be as effective as water only flows through the upper part before exiting the sidewall (to chamber 2).

The back of the media caddy is accessible by a thin guillotine-style door that slides in/out from the top.

removable access plate on the InTank Filter Media Basket

InTank provides an insert that you can glue (I’d suppose with gel superglue) to the inside of the tank to close up the bypass.  This part is 3D printed.

InTank Chamber 1 Media Basket – Specs and Dimensions:

Hopefully, the above description gives you a good idea of what this filer media caddy does, but I’ll backtrack a bit and offer some overall specs and dimensions.  As always, dimensions are as measured by myself (in millimeters, converted to inches) from the unit I purchased.  Dimensions may vary from unit to unit and InTank could change their product over time.

What Comes with the InTank’s Chamber 1 Media Basket:

  • Media Caddy constructed of acrylic.  Three shelves with the center being removable. Removable back for access to the filter media.
  • (1) overflow insert
  • (1) bypass plug
  • (1) ‘InTank’ decal
  • (1) package of Swedish Fish Candy

accessories that come with the InTank Media Basket for Fluval EVO 13.5

Dimensions of InTank’s Chamber 1 Media Basket for the Fluval EVO 13.5:

  • Overall (outside dimensions): Height = 286 mm (11.26″); Width = 90 mm (3.54″); Depth = XX mm (XX”)
  • Chamber Footprint (inside dimensions): Width = 82 mm (3.23″); Depth = 60 mm (2.36″)
  • Chamber Heights (inside – between shelves): Top Chamber = 42 mm (1.65″); Middle Chamber = 85 mm (3.35″); Bottom Chamber = 147 mm (5.79″)
  • Acrylic Thicknesses: Front and Sides = XX mm; Back (sliding panel) = XX mm, Shelves = XX mm.

The bottom chamber has a slot cut to accommodate the fin that is part of the stock EVO 13.5.

chamber 1 slot in the InTank Media Basket for Fluval EVO 13.5

Usage and Tips for InTank’s Chamber 1 Media Basket:

Not much to describe, but hopefully you can understand from the photos how this media caddy works.

InTank Chamber 1 Media Basket installed in a Fluval EVO 13.5

Slide the back door upwards and out of the way to load/unload media from the middle and bottom chambers.

The top tray is accessible directly from the top. However, I find it easier to remove and replace the filter floss by first pulling out the overflow insert.

By the way, this overflow insert is a 3D printed part – perfectly acceptable for this small component and it the quality of manufacture is good.  This is a critical part in making the whole setup work.

3d printed overflow insert

The tolerances of the media caddy (overall) are tight and precise, but there has to be some ‘play’ to allow the unit to slide downwards into place.  The overflow insert helps to ‘wedge’ into the gap to press the caddy tight to the back glass of the filter section and reduce the area for water to possibly bypass.

overflow insert installed in the InTank Media Caddy for Fluval EVO 13.5

The overflow insert also creates a smooth and enclosed flow path for water to flow into the top chamber. This ensures that almost all of the water from the display section will go through the filter media sections and not ‘bypass’ the spaces between the caddy and the tank walls.

I have a separate page where I detail filter media options.  For our use, I have stuck with the following:

The water level in the display section of the tank is constant and is dictated by the configuration of InTank’s overflow insert.  InTank redesigned the product (January 2020) to adjust the water level lower.  I had the old version and indeed, the water level was too high – there was a risk of splashing out of the tank with an aggressive wavemaker.

water level in the Fluval EVO 13.5 saltwater nano with InTank's Filter basket installed

The new version is configured with the water level to be about XX mm (XX”) below the top rim of the tank.  At first, I felt this made the water level too low, but I’ve grown to get used to the look.

One thing to note (and I discuss this in-depth in my ATO review) is that changes in water volume affect the level in the back chambers but the water level in the display section will remain constant.

Best practice is to adjust the system volume so that the water covers your filter floss but not so high that it overflows over the top of the acrylic sides of the media caddy.

filter floss installed in InTank's Chamber 1 Filter Media Basket

Pros / Cons and Final Thoughts on InTank’s EVO 13.5 Media Basket

Let’s wrap up some final thoughts on this great aquarium accessory:

Pros of InTank’s EVO 13.5 Media Basket:

  • This product solves the major shortfalls in Fluval’s design. It corrects the flow problems and gives the end user a better way to manage filter media in their saltwater nano.
  • The construction is excellent and very high quality.  The use of clear and green tinted acrylic, along with the etched logo, is very attractive. Tolerances are excellent allowing effective removal and maintenance while maintaining flow through the unit.

Areas of Improvement for InTank’s EVO 13.5 Media Caddy:

  • The caddy is hard to remove. InTank has actually listed on their website as a feature a “Built-in finger hole for easy installation and removal”.

finger hole lift feature of the InTank Chamber 1 Media Basket for Fluval EVO 13.5

This is a little lame – when I change out items on the middle chamber, I often want to leave the filter floss in place; the finger hole isn’t accessible.  It would be nice if they at least put some textured indents for fingers on the inside faces to help lift it out.

  • The cost is questionable. This filter media caddy is currently priced at $60 USD.  In context, the EVO 13.5 is priced from Fluval at $200 USD.  That makes this single accessory 30% of the cost of your tank.  I’ll get into value more in a bit, but I feel the price is a tad high.

Alternatives to InTank’s EVO 13.5 Media Basket:

Alternatives I see are DIY solutions, such as a solution made from Plastic Light Grid (EggCrate) and zip-ties.  The trouble with DIY is that it will be challenging to deal with the flow characteristics of Fluval’s stock tank – InTank’s product has a big advantage in this area. Also, the materials do have a cost associated with them as well as the time and effort involved.

I’ve started to mess around with 3D printing and making your own filter media caddy is a viable option.  Challenges are the know-how to model the part, the size of the part (The height is at the edge of what can be printed on consumer 3D printers), as well as the cost of filament.

I recently made a custom filter caddy for our Fluval Spec V.  It turned out great, but took several iterations (about 3 print cycles) to arrive at the final version.  Each print used about $8 USD of filament for the print, so the cost of materials was not insignificant.  All of this is to say that when you factor in the time, effort, and cost of filament, an out-of-the-box solution like InTank’s caddy appears to be a better deal.

Final Thoughts – Is the InTank EVO 13.5 Media Basket Worth It?

It’s often said, something is worth what you are willing to pay for it. In the case of InTank’s Filter Basket – it is worth the price . . . for this specific application.  The way this product deals with the Fluval EVO’s flow shortfalls make it worth the money.

It’s also said that you should “Buy once, cry once” with the meaning being to get what you need the first time.  In the context of how long InTank’s caddy will last, the cost ends up being no big deal in the context of functional improvement and enjoyment gained.

4 thoughts on “InTank Chamber 1 Media Basket for Fluval EVO 13.5 Review

  1. Are you still using the original Wayfair cabinet you purchased at the beginning? Any signs of sagging? If not, what is that piece of furniture called on the website? Thanks!

    1. I am using the same cabinet. No signs of warping, sagging, or any changes at all. I did add some wood support on the centerline/underside to help it out a bit (before setup), but not sure how much it does or if it is necessary.

      Miracle of miracles, I tracked down the model of the furniture we purchased as a stand: Westhoff Solid Wood 1 – Door Accent Cabinet (although the price shown currently is about double what we paid in 2020).

  2. Hi. I am considering Intank basket for shrimp tank spec V

    Do you think if I had 2 tetra and shrimp that I would likely like this product or overbuying? Since you use for saltwater ?

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