AquaCity™ 250SB Bio Balls Filter Media for Aquarium Fish Tank Pond Filtration by Aquacity</br></br><div style="text-align:left"><b>[Product Information]</b><br><ul><li>1" Ball in diameter; approx. 250 balls in 5 mesh bags;</li><li>Good to use in both fresh & saltwater tank; offers mechanical and biological filtration with inside sponge.</li><li>These bio balls are lightweight and typically float. They float so that the surface area can be close the air so that the bacteria get oxygen to thrive.</li><li>Bag size: 8" x 5.5"</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/51c6sVUdlkL.jpg' noproxy></br><img src='http://ecx.images-amazon.com/images/I/51QsVjU1cTL.jpg' noproxy></br>