The filter technology utilizes UV lights that kill and remove any harmful bacteria, pathogens, algae, or any free floating micro-organisms from your ecosystem. The UV bulb will purify your aquarium or pond. You can utilize this device in freshwater aquariums, saltwater aquariums, and outdoor/indoor ponds. For freshwater aquariums, it will help remove any unwanted green hair algae or microscopic bacteria that can cause ich or diseases for your fish. For saltwater aquariums the UV sterilizer can remove and prevent a number of problems. It aids in preventing and removing any red slime algae or harmful cyanobacteria that can threaten your saltwater fish and corals. UV sterilizers are invertebrate safe, so they will not harm your shrimp, snails, and hermit crabs. For ponds, the UV sterilizer will remove any free floating bacteria such as algae, insect larvae, and any harmful bacteria that can threaten the water conditions. This will keep the nitrates down, the water crystal clear, and bacteria/algae free. The Oxyful ultraviolet sterilizer can be installed vertically or horizontally. The best place to install your UV sterilizer is After the filter. If it is necessary to install the sterilizer before the filter, adequate pre-filtration should be used to prevent the quartz sleeve from breaking from debris. The rubber ring will go in between the inlet/outlet, while screwing the nut on top to tighten the seal. On/Off is managed through the plug it is connected to.