These high quality filters from the German brand Oase provide excellent filtration due to their large filter volume. They come with an easy clean pre-filter chamber that can be cleaned during regular maintenance sessions to remove detritus and other dirt from the aquarium system. The BioMaster 250, 350, 600 and 850 filters all come complete with the ThermoFit adapter which allows you to incorporate the Oase HeatUp Aquarium Heater into the same unit. This removes hardware from the display aquarium that would otherwise distract from your beautiful aquascape. Add the Oase HeatUp 150 to this filter to remove the heater from the display tank that would otherwise take up room and distract from your aquascape.