Probably 1”. You need at least 2-3 fingers worth of space to allow the air to flowHi, guys. To add to this four year old question; How close to the tent roof can the 300W Mars Hydro 48 safely get? it supposedly runs at ~30C. There is answers everywhere about height from plant but none that I've seen about roof to led. I'm asking because I want to put one in a 400x400x1200mm tent and obviously, every cm in it, is precious real estate for me.