Deep Blue Professional ADB41013 2-Pack Activated Carbon in Jar with Media Bag, 39-Ounce Laboratory grade activated carbon captures micro and macro organic particles Removes odor, spent medication, discoloration in water and various toxins through absorption The large surface area on carbon granules promote colonization of beneficial bacteria essential to a healthy aquatic environment Safe for both freshwater and marine aquariums Includes two 39-ounce jars with media bag