It depends on a few things. How big your plants are, the smaller they are, the further away you should put your lights. What the temps are like? You say 77 at canopy level, is that the hottest it gets when your lights have been on for a few hours? I'd say have them about 24" away for now, then move down to 18" in a couple of weeks.
hudson88 Reviewed by hudson88 on . LIGHT DISTANCE FROM PLANTS (PICS) how far do i keep 2 1000w MH lights from my plants? Rating: 5