What are the physical differences between a crocea and a maxima? I recently bought a clam but dont know what species it is (i forgot). From previous research i suspect that it is one of these two. Is 4*54W T5's on a 72 gal. bowfront sufficient lighting for growth for either species? What species of clam can i keep under these lights ( the sand bed is 20 inches from the surface, and the lights are suspended 3 1/2 inches from the surface). How can i tell if a clam is not getting enough light, besides its death? thanks to anyone that can help me out.