http://www.bghydro.com/BGH/customkititems.asp?kc=HLMH10SS&eq= if you go to that link and look under the bulbs tab there is a lot to choose from. I need advice as to which one is best. Is the hortilux really worth it? increased yield? or is the regular bulb ok? spending over 100 on a bulb should do something and if so what? thanks for the help guys