you will have to mess around with it and try different things for yourself in your setup those 8U and 11U CFL bulbs seemingly put out the best light in equal amounts 360 degrees around them from the sides of the U-bulbs so ideally, you will find that hanging it vertically (or having it sitting straight up from the ground on a stand or something) and having your plants around the light would be best... the thing is that most people notice those bulbs are not worth the hassle they put out a lot of heat, just like a hps, yet they lack the lumens and PAR switch to hps and get better growth, yields ect. i have a 250w feliz 11U that has been sitting somewhere in a tote for a couple years now collecting dust