A fully swiveling spherical pump head, modular design and other advantages come from the aquaball concept. The special feature of biopower is that it offers multi-stage filtration like an outdoor filter. The closed filter baskets are filled with highly efficient filter media (e.g. SUBSTRAT-pro). A suction basket containing filter cartridges for mechanical and biological pre-filtration. Water drawn in at the base is pumped up through the various filtration layers and returned cleaned to the aquarium.