I used a P600 for my 2nd grow (White Widow Auto.) They are bright! I found in veg that I had to keep the lights at about 27"-34" with the 'veg' LED's only on. After the flip to flower, and turning on both the Veg and Flower LED's, the plants grew quickly and nicely towards the light. I found that 18" was a bit too close, and kept backing off to about 24". I was in a 78" tent and found that 4 rope ratchet light height adjusters worked better than the supplied light hanging stuff, as I was able to move the light several inches closer to the top of the tent, as the plants flowered and tried to grow into the light. I got about 1/2 G/W in a 2x4, and the upper bud quality was stellar. Good luck!
Yes! I've come to realize that you do have to keep these light far away from the plants. Which is really hard to do when my tent is only 60 inch tall. I might have to get a bigger tent if it poses a problem in the near future
You can kind of figure out the max height your plant can get in the 60 inch tent. From 60, subtract the height of the pot, the closest you can get the LED's to the top of your tent, and the max distance at flower. Made up example: 60" - 8" (pot height) - 4" (lights tied to cross poles) - 18" (min led to plant distance) would leave room for a 30" plant. The Kush will probably get 2x - 3x its current height as an Indica. The AK48, a sativa based, probably a bit more, assuming you are growing bushes.
