If you are not sure which order you should be placing the filter media in the FX6, then you can take a look at this Aquarium Blueprints guide to find the correct placement.
About the FX6 Media Baskets
The Fluval FX6 canister filter comes with three white full-sized baskets. Each of these has an outer rim with a hole in the middle.
The top and middle baskets each come with a middle red half-sized media basket if you want to separate the top and bottom portions of the middle hole.
Top Full-Sized Media Basket
When you take the top off of your FX6, you should see the top full-sized media basket. The top-most unit is designed for mechanical filtration as it should prevent the biological media in the middle full-sized basket from getting clogged up with fish wastes.
So, along with the Bio-Foam sponges covering the outer rim, you should see two Bio-Foam+ sponges, which are separated by a red half-sized basket, in the middle area.
Middle Full-Sized Media Basket
The middle full-sized media basket is used for biological filtration. Here, you should also see the Bio-Foams on the outer rim. In the middle hole are the Bio Max Ceramic Rings, which are separated by the red half-sized basket.
Bottom Full-Sized Media Basket
The bottom-most full-sized media basket has been designed for chemical filtration. Just like the two higher baskets, this one also features the Bio-Foam sponges lining up on the end.
The carbon pad, or any other chemical filtration you plan on using, should be placed at the bottom of the middle hole.
Recap
To recap, Fluval recommends that you use the following media order when it comes to the full-sized media baskets:
Top Full-Sized Media Basket:
- Outer Rim: Bio-Foam sponges
- Middle Area: Bio-Foam+ sponges or other mechanical filtration
Middle Full-Sized Media Basket:
- Outer Rim: Bio-Foam sponges
- Middle Area: Bio Max Ceramic Rings or other biological filtration
Bottom Full-Sized Media Basket:
- Outer Rim: Bio-Foam sponges
- Middle Area: Carbon pad or any other chemical filtration
If you need a visual aid when it comes to identifying the recommended filter media placement, you can take a look at the 5th page of the manual, which you can download the PDF version of with this link.
Of course, you are able to modify the media placement to your liking. In our case, we don’t use any chemical filtration in our tank; therefore, we ended up removing the carbon pad and then using the empty space to add more biological filtration.
We also replace the Bio Max Ceramic Rings with Seachem Matrix as the latter is able to remove nitrates to go along with the ammonia and nitrite compounds.
For the sponges, you don’t need to stick with Bio-Foam or Bio-Foam+. Any other sponges made for fish tank filtration should work.
With that said, we recommend that you use the Bio-Foam and Bio-Foam+ that came with the filter for as long as possible until they either start to break down or get clogged frequently. Otherwise, these sponges don’t need to be replaced.