ty pepper....i used an off white piece of foam to gauge how close i could get without the light seperating. 12in was about it. so i went from 24 to like 14. seem to be growing good, ill take a few more out of there for pics this sun. i dont know if its my eyes after being in there, but they look almost flourecent when taken out. definitely differant appearance than HIDs. but like i said, your eyes are fucked when you leave the room, everything has a green glow, like a green flashlight in a dark room. green haze....ironic?....lol