The BioMaster line of premium external filters are perfect for marine and freshwater aquariums. The BioMaster 350 boasts 4-stage filtration in a compact design. Biological, mechanical, chemical, and prefiltration all work together to provide your aquarium with optimal water quality and clarity. The BioMaster filters are designed with sealed filtration pathways to ensure water flow is getting the full benefits of prefiltration, filter media for clearer water, Hel-X Biomedia provide a large suspended settlement surface for microorganisms, and activated carbon for ideal nutrient reduction and removal of toxins. The EasyClean prefilter module can be removed and cleaned separately from the rest of the filter for high efficiency and to extend the life of your filter. Created for convenient placement under the aquarium. Customize your prefilter by combining coarse, fine, ultra fine, and activated carbon filter foams.