Sorry for the noobish questions; converting my veg tent into a two-level affair (with a 400HPS up top for vegging plants before they go into my flower tent) and using fluoros for the first time since I used to be an aquarium enthusiast many moons ago.
6 inches seems a little on the far end ...... it is definitely a pain in the ass to be moving the lights up and down all of the time though.. i just got a t5 for this last grow, and i and my plants love it.. i find that moving the plants down instead of moving the lamps up is easier in my case... i keep my t5 about two or three inches away from the top of the tallest of them... i didn't move the plants one or two days and the top of pne plant did eventually get a lil burnt... nothing like an hps burn, but burnt non the less... fluro tubes tend to fade very fast at a distance, so this is why it is recomended to keep them right on top of your plants....