Bio Rio G is a sintered glass filter media suitable for biological filtration. Because it is porous, and its surface area is quite big, many filtration microorganisms settle and demonstrate high filtration performance. The pieces are irregular. And when a filtration tank is filled with them, gaps are easily to be formed. So they hardly cause clogging. Because it is unlikely to impact water conditions such as pH and hardness of water, a long term stable filtration can be achieved.