The top of the soil drys out quickly due to the fans blowing on the plants. But when you stick your finger down in a half inch to an inch, it's still nice and damp. Lights are above the plants by about 3 feet at least so I don't thnk it can be light burn - plus I'm just running two TEC lights with 8 bulbs each. And the problem with the leaves is not just at the top, but all throughout the plant.
the clone in the cup has NOT been fed so It can't be nutrient burn. And I don't think humidity is the problem as it is running between 60 and 70 percent.
Any more thoughts?