I've been keeping BTAs (entacmaea quadracolor) for several years with good success. HOWEVER, I consider 6 months to be the minimum time after establishing a new tank to try adding BTAs. Better to wait 12 months. If/when you get one, please try to get an aquacultured BTA, not wild caught - they're declining in the oceans due to over-collecting for the aquarium trade (I'm seeing fewer on each subsequent dive trip to micronesia). Secondly, you must ensure that no power head or filter intakes can be reached by a roving anemone - they will end up shredded. Finally, as to "how much light". I have a moderately well lit 180 gallon, 2 ft deep tank. Combined output of my CFL lamps (no MH) and skylight over the tank provides about 5Watts/gallon. My BTAs (15 of them) have selected anchor sites within 12 inches of the water's surface.