I'm not an expert either, but I've learned a few things. Height of the taqnk is the main concern, and since your tanks is so small, I think you could keep at least a dersa, but it probably will eventually get to big for the system. Also, not just the wattage, but the type of bulb makes a difference. T5's seem to be the flourescent bulb for clams. Maybe Skinz78 can drop in and enlighten us, because he really is an expert.