The Grech CBG-Series Hang-On Back UV Filter comes with a diverse and unique design. While being suitable for freshwater and saltwater aquariums convenient for daily use. The filter is beautifully crafted to allow a simple installation and silent operation. Water flow can be control accord to your aquarium needs. The CBG-Series has biological and mechanical filtration and comes with active carbon and bio media. The CBG-Series also features a 5W UV Sterilizer which can be turned on and off. The UV Sterilizer helps in eliminating algae, keeping aquarium water clear, and aids in the health of aquatic animals from free-floating parasites. The controllable surface skimmer can reduce surface oil from your aquarium tank.