The media baskets in the XP3 are very customizable.
You can set them up any way you like.
For instance if the tank requires more bio, then have 2 baskets contain biological filtration.
1 basket would then contain floss for mechanical filtration.
If the tank needs meds or discoloration removed, then use carbon for chemical filtration.
The 3 types of filtration are biological, chemical & mechanical.
You can observe the tank and determine what it needs to operate effectively.