If you run carbon and GFO in your reef tank, chances are you might be doing it wrong. Hobbyists usually run carbon, GFO, and other media in the reverse flow (upward flow) style media reactors, and more often than not, the flow is a bit too excessive. If that is the case, the media could tumble or at the very least “boil” at the top. When this happens, the media crumbles on itself, which could release particles back into the sump or other parts of the aquarium. While this doesn’t necessarily have an immediate negative impact on the overall health of the aquarium, the particles could cover corals creating a visually unpleasant sight or it could block out light to photosynthetic organisms.