what are the dimensions of that tank? I couldn't really get much to grow under my sundial either. I got shrooms to grow, but that was right under the surface with the light on the plastic legs. Also, things won't die, but they won't grow either if your CA and Alk are low. a large (40%) water change usually makes things multiply as long as you do not do them too often. Kind of like a forced bloom for the corals. FEED FEED FEED, BAM, huge water change.