I have 260w JBJ Formosa PC lighting that I like a lot but if I had to do it over again I would probably go with a Metal Halide/Power Compact combination! Lighting is the most important thing in your tank so do your research! Make sure you get higher end spectrum bulbs (10000K daylights, 7100K actenics as lower end spectrum bulbs cause algae problems!) There is a very general rule that says you need 3-5 watts per gallon for corals, but if you want to be able to keep all types of coral effectively (and your clam) you may want to bump that number up to 5-7 watts per gallon (acropora's in particular require more light). Good luck!