Nutrafin Clear Fast Particulate Water Clarifier is a responsive fast acting formula that will clear cloudy water in 1 to 3 hours. Suspended floating particles such as algae dirt silt fine sand too small to be removed by filtration are clumped together by a unique ionic attraction that forms larger particles that are then easily trapped. Use Nutrafin Clear Fast for cloudy aquarium water as a result of: tank disturbances floating debris aquarium maintenance new gravel introduction or suspended algae. Nutrafin Clear Fast Particulate Water Clarifier Features and Benefits: - Freshwater aquariums only - Safe for all aquarium inhabitants - Fast acting! Works in just one hour - Clears cloudy aquarium water by precipitating organic and inorganic particles.