I don't use Fluval, but three layers:
1-coarse foam and medium foam
2-bio-media (everything from crushed coral to plastic scrubbies to sintered glass balls). BTW I notice no better performance from the more expensive media
3-fine filter pads
Coarse pads around the sides. In the top tray I put a medium pad (in red tray), under that is a fine pad or filter floss. 2nd tray is full of biological media (I pulled the red basket out for the 2nd tray). 3rd tray I put a mesh bag filled with crushed coral on the very bottom and then filled the rest of the tray with more bio media.
I'm still tinkering with setups and open to changes but as of now I'm running the original pads around the sides and then, from top town, Black fluval sponge, poly-fill, blue fine sponge, 2nd tray is full of biohome ultimate media, bottom tray, lava rock, Purigen, Polishing pad.
I use the stock coarse pads around the baskets. I use Seacham Matrix (3.5lbs) as follows: bottom tray filled to the max with 2 100ml bags of purigen and a medium filter pad on the bottom of the tray, middle tray filled with Matrix and no filter pad, top tray I use both a bag of Matrix and crushed coral with a medium and fine filter pad on the top.
I am considering replacing the Matrix with crushed coral in either the 1st or 2nd basket. Thoughts?
When the purigen is exhausted, I replace them. I no longer do the recharging at the moment. I recently purchased the 250 ml bottle of purigen, which is cheaper than the 2 pre packaged product.
Here's a link to the fine filter pads I use, which I think is great bargain. The course and medium pads can be rinsed and reused