Reduces dissolved toxins from fish waste. Works in any filter. Phosphate free. For use in freshwater aquariums. Keeps water clear and ammonia-free. Helps promote fish health by improving water quality. Unique Blend Of High Grade Activated Carbon And Ammonia-Removing Media. The Carbon Removes Dissolved Organic Waste, Colors, And Odors. The Ammonia-Removing Media Removes Toxic Ammonia Caused By Fish Waste And Organic Debris. 37 OZ