AQUANEAT Aquarium Filter 5W UV Bulb Green Water Killer Submersible Pump Filter 132 GPH for 75 Gallon Fish TankBrand: AQUANEAT Features: It helps improve water quality and clear free floating algae, it can help turn green water to clear in 3 to 7 days. Please note, UV filter is effective against algae blooms (e. g., green water), but it doesn't address physical cloudiness. Also, UV filter could only kill free floating algae, also called "green water". The algae covered on tank won't be killed by the UV filter, because they attached themselves on the surface