From the Manufacture
Clear up cloudy aquarium water in no time! Water Clarifier tablets clear cloudy, discolored water, and remove odors caused by decayed organics (fish waste, dead plants, overfeeding, or bacterial blooms). Also neutralizes iron present in water which causes stains on aquarium glass, hoods, lights, ornaments, and accessories. For use in established aquariums only. Do not use on newly set up aquariums.