Aquarium Pharmaceuticals Activated Filter Carbon 22oz.

Pour half a cup of this stuff for every 10 gallons into a nylon mesh bag, rinse well under tap water, listen to it sizzle, (sign of good carbon!) and place into your filter as the last step of filtration. In other words, carbon is a chemical type of filtration and should be the last thing your filtered water passes through before it goes back into the tank. I place mine on top of my biological medium in my Aquaclear filter. I watched my "tea" colored water clear up in just over 2 hours when I placed this in my filter. You should always have fresh carbon in your filter and change it about every 4 weeks. This way you don't find yourself scrambling to get some in the tank to clear it up before company comes over! ;) Nothing else to say, it's good stuff.