This advanced filtration material is more effective than carbon alone! Convenient pouches treat up to 55 gallons. Provides a home for massive colonies of nutrifying bacteria that rapidly develop a biological filter in both fresh and saltwater aquariums. Space-age porous polymer allows for rapid transfer of oxygen and water. Fits any filter. Removes organic waste in fresh and saltwater aquariums. Contains no phosphates. Removes toxic heavy metals in fresh water. Removes aquarium pollutants, such as toxic gases, water discoloration, foul odors, and phenols. It is easiest to add this to the filter when you are doing a water change. I however did not do a water change the first time I used it. Johnnie Turtle had very cloudy very gross water and I put this in the filter, within 2 days the water was crystal clear. It does need to be changed every couple months. I have found it lasts a little less than the packaging recommends but I believe that is because it is meant for fish, which are a little less messy. Works great for reducing odor and clearing water.