i just bought a purple coloured 4 1/2 inch clam and I would like to know where to place it. Do i put it on the sand bed or on my life rocks nearer to the surface? Must I position it to face the current or can I place it the way I fancy? I understand that small clams need to be fed with phytoplankton and bigger clams only need strong lighting. So is my 4 1/2 inch clam a big clam or a small clam?