If you are unsure about the correct placement for the filter medias when it comes to the Fluval FX4, then you can check out this guide from Aquarium Blueprints to find the recommended order.
Media Baskets
Before we begin, it is important to note that the Fluval FX4 has four media baskets with two of them being full-sized and white. The other two baskets are half-sized, red and fit in the middle of the full-sized versions.
Top-Most Full-Sized Basket
The first Full-Sized Basket sits at the top. It should be the first basket you see when you remove the top-lid from the canister filter.
The border of this basket is surrounded by the Bio-Foam sponge.
In the middle, you will find the top-most Half-Sized Media Basket.
Top-Most Half-Sized Media Basket
The first Half-Sized Media Basket you see is mainly used to prevent the Biomax Ceramic Rings underneath it from getting too dirty. Therefore, you should have a sponge in this small basket.
For the uninformed, the Fluval FX4 uses the Bio-Foam+ for this Half-Sized Media Basket.
So, for the Top-Most Full-Sized Basket, you should place the Biomax Ceramic Rings first at bottom of the middle area. You should then place the Half-Sized Media Basket, with a sponge for mechanical filtration, on top of the rings.
Bottom-Most Full-Sized Basket
The Bottom-Most Full-Sized Basket also uses the Bio-Foam sponge for its borders. It also has a middle area that you can use for multiple purposes.
Bottom-Most Half-Sized Media Basket
By default, the Bottom-Most Half-Sized Media Basket is used to hold the Biomax Ceramic Rings and separate them from the Carbon Pad underneath it.
Therefore, the carbon, or any other chemical filtration media you plan on using, should be placed first at the bottom in the middle area. Afterwards, you can put the Half-Sized Media Basket, with biological filtration, on top of the chemical filter media.
Recap
To recap, you should set up the filter media of the FX4 in the following placement order:
Top-Most Full-Sized Basket:
Border:
- Bio-Foam sponge or any other sponge
Middle Area:
- Biomax Ceramic Rings or any other biological filter media at the bottom
- Half-Sized Media Basket with Bio-Foam sponge or any other sponge on top
Bottom-Most Full-Sized Basket:
Border:
- Bio-Foam sponge or any other sponge
Middle Area:
- Carbon Pad or any other chemical filter media at the bottom
- Half-Sized Media Basket with Biomax Ceramic Rings or any other biological filter media on top
If you need a visual guide, then you can check out the fourth page of the digital user manual PDF.
It is important to note that your canister filter should remain effective even if you don’t follow the guidelines when it comes to the media placement order.
In our case, we ended up removing the Carbon Pad from the bottom as we don’t use chemical filtration in our tank. Instead, we replaced it with more biological filtration media.