At first I was using a pair of 24-inch GE full spectrum growing lights, that were about a foot from the plants. I think this was way too close, as you can see some tip burn and wavy leaves, so I moved them a bit further away. I also started reading up and watching videos on cannabis and light, and decided to move on to 2 VIVASPECTRA P1000 LED grow lights, rigged together, and kept about 18 inches away, at just under 25% output during the first few weeks. I figured the higher output of the lights, as well as turning them down and moving away, would keep the direct light burn issues, and it worked out. I would keep the lights the same distance and turn the light output up bit by bit every couple days as the plants grew more.