single lense reflectors.
nick with new style lighting its best not to look into the whole watts per gallon.
with T5s you want one lamp per 3-5 inches of tank from front to back, depending what types of corals you want to house, T5s can also penetrate up to 30" of depthwith the right ballast reflectors and lamps.
are use to light a 24"x24" area and the wattage all depends on the depth, a 250 watt is good for about 24" where as a 400 watt will do 30" but some may use 1000watts to light up a 30" reef. 150 watts are just pointless and only good for small nanos
LEDs are a totally differnt rule on its own, you can get the same penetration and PAR with half the wattage depending on optic selection and LED