lighting retro fit...

i have a 30L tank that i just got and im trying to fit a fluorescent bulb into the light hood i got with it because it was just for a regular screw in bulb.. so i picked up a 36" single fluorescent fixture at lowes.. so now im retro fitting it onto my old tank.. i can do it but my question is.. is one good enough? or would i need 2? or should i juss fit a T5,8, or 10 in there? im running a philips 5000k 30 watt bulb on it its looks ok but i dont know if i should go brighter. im thinking of overdriving a single bulb what do u guys think? lmk thanks..

ya sorry there are no plants as of yet.. ive been planning too but i dont know what kind to put yet and havent read much about plants.. if i did are there any plants that could be supported by one bulb?