The Reef Octopus MF800B Complete Media Reactor steps up media capacity from the MF300B in the same all-in-one hang-on-back format — feed pump, hoses, and fittings included, so you only need to add carbon or GFO media. It's built to keep reef and mixed saltwater water quality stable without dedicating sump space to a plumbed reactor. Best for: reef and mixed saltwater tanks needing more media capacity than the MF300B Setup: hang-on-back, complete kit — pump, hoses, and fittings included Materials: solid construction designed for stable, consistent flow through the media bed Step up to the MF800B from the MF300B when you're running through media faster than expected, or dosing a heavier chemical filtration load.Compatible replacement parts: feed pump kits and hoses for the MF800B.