i have 260 watts of pc lighting over my tank right now. they also told me he would be ok under this lighting so long as i keep my water in good condition and keep my calcium levels up. there is a pic in my gallery of the tank that shows where the clam is positioned. not a very good pic , but i think you can see it . i'm pretty new to this so your input is helping. hopefully i can keep the clam, but i want it to do good.