Brightwell Aquatics "Xport NO3 Dimpled Brick"</br></br><div style="text-align:left"><b>[Product Information]</b><br><ul><li>Superior-grade filtration brick has the highest porosity and largest useable surface area， per unit weight or volume， of all filtration media available anywhere</li><li>Provides huge amounts of aerobic and anaerobic surface area for efficient bacterial colonization</li><li>Provides over 71，000 square feet (6，596 square meters) of surface area per liter of medium</li><li>Each brick has about 100，000 square feet of useable surface area for bacterial colonization</li><li>Doped with Sulphur to act as an electron donor to accelerate the denitrification process in ponds， freshwater， or marine aquariums</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/41eLFy5v5sL.jpg' noproxy></br>