My Emperor 400s have 2 slots for primary media and 2 for secondary filter media cages. The rite size filters in the primary slots are very coarse and have only a tiny amount of charcoal for chemical filtration. I would like to take out the rite size media and replace them with filter media cages too, but I can't find where to by spare filter media cages for the Emperor 400s. Has anyone solved this problem?