How you doing Supergroomer....pretty girls......about your question.....i run a 400 adn 700mars.....we had this disscussion on a journal i follow, but anyway i try not to let them get any closer than about 12 inches....12 to 18 so i say your on target.....you can run them closer as stated above, but the only problem with that is you dont get the full spectrum evenly over your canopy....the leds need so much distance from the canopy so that the individual leds can blend the same spectrum over the canopy....the closer you get the more focused the individual leds will be on one spot of your canopy.....like above i have ran them close like that before with no bleaching or burned leaves but once it was explained to me about blending and so on i now keep a minimum of 12 inches.....hope this helps