EHEIM reeflexUV is yet another typical innovation from EHEIM: due to a built-in reflector the microorganism killing UV-C radiation is significantly increased and whereas in conventional UV-sterilisers the water is directed via detours past the UV-C burner, in the  EHEIM reeflexUV water it takes the direct route. There is no loss of performance, you need less energy and. The level of effectiveness is 1.8 times greater. EHEIM reeflexUV should only be used in conjunction with the filter, in order to reduce small organisms (microorganisms, algae spores etc.) in the aquarium.