I'm in the process of changing things around and I may no longer use the rack. However currently I have Chemipure Elite in the bottom, chaeto in the center, purigen on the top, then above the media rack I have Marineland Rite Size A filter pads which are filled with carbon. They are typically used in Marineland's HOB filters. Now, I have a biopellet reactor set up and running but it has not yet started to do it's thing. It takes a few weeks. I also have a BRS reactor that I'm going to run GFO and GAC in but I need to get another pump first. Once these take hold, the media rack is going to be removed.