I have all sizes in my 180. LOVE this stuff!!!!! It looks absolutely amazing once you get a coat of algae on it. My fish love it too. Just be careful to run your fingers along all edges before you put it in your tank (inside the "rock" too). Because it's molded - there are some "excess" spots that can be quite sharp. Would hate to have any of my fish run into these if spooked. However, they break off pretty easily and then are fine.