Hey thanks for info ......i have been growing for awhile but was not real sure of the distance...the light has been around 18 to 24inches above and I have had no problem with burning. in a room that is 7x7 what do you think...how many plants in 2 gallon pots would be good. one more thing how tall do you let them get before they go under the big light. my fans are big enough to handle the heat and fresh air . thanks to all:rasta: