The leaves at the very top of my two tallest plants are getting "claw", you can see it a bit in the photo above, the leave tips are pointing down. Its only at the very tops of the two tallest plants, though the rest of the plant is fine.
I suspect they have grown too close to the lights, so im going to raise the lights a bit.
The lights are 3 x 600W's all in cool tubes, and the plants that are effected are about 10 inches from the tubes. If I put my hand there for like 30 seconds, its warm, but I wouldn't say "hot".
Anyway im going to try raising them a bit and see what happens.