Hello, , so I have a few blackberry kush at 6 weeks into flower. 12/12. They are all fed with the same res water, I'm using gh flora nutes, water temp is 74.5° and pH is 5.85, the res is oxygenated and it's a drain to waste system. E/c is 1.8 and ppm is 1201. Room is set at a temp of 78.0° day and 69.9 at night. I'm running four scrubbers, and 3 600watt hps lights. Fans and fresh air intake. No light leakage, so, here is the deal, a few of my plant have they symptoms of N toxicity. Meaning the leaves are curled or clawed under very badly..... the leave color on these few effected plants is pale green. None of the leaves on any of the plants have nute burn, meaning the leaves even on the sick plants do not have any brown tips or edges.....my medium is coarse perlite and a little vermiculite. It's 4 perlite to 1 vermiculite to be exact......I've flushed them a week ago and it made no changes...any information anyone can give me would be greatly appreciated. ....thanks in advance. ....mateo feo