I think you can put the filter floss on top or right after the sponge. I'm actually using right after the sponge to polish up the water before it gets to the biomax. I'll eventually place the bag of Purigen last after the biomax for that extra level of polishing. Have you used Purigen? If not, you should! Great stuff! It can interfere with the cycling process so just make sure to add that after. You should also stick your bag of biomax in one of your established tank's filters while you're still setting up your tank's hardscape and planting. That way you'll have some migrated BB on there which will speed up the cycle. Well, you probably know all this already.. so it's just a friendly reminder and for those new to the hobby reading this