Hydor Professional External Canister Filter Media， Activated Carbon， Saltwater</br></br><div style="text-align:left"><b>[Product Information]</b><br><ul><li>Highly adsorbent Saltwater activated carbon eliminates bad odors and polluting substances</li><li>400gm pouch</li><li>Carbon can be substituted by Zeolite， which is used in some marine aquaria to keep nutrient concentrations low for the benefit of corals adapted to waters</li></ul></div></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br></br><img src='http://ecx.images-amazon.com/images/I/51e9wRNW3GL.jpg' noproxy></br><img src='http://ecx.images-amazon.com/images/I/31hdO-2LHPL.jpg' noproxy></br>