In my future tank setup, I've got this media setup, in descending levels:

FLUVAL PreFilter Media
--Separator--
Coarse Filter Plastic Bio Media (See Image)
Carbon Bag
--Separator--
FLUVAL BioMax Media
--Separator--

Assuming that the water flow goes from the top and out the bottom hole, this setup is valid, correct?

And also, are plastic sponges like this good for media?:



It's okay if they're not, I'm just asking.