Quit being a "helicopter grower"... it's just growing pains, unless your whole plant looks like that. You just flipped, they are going to go through a transition. Thanks for the finger prints.. gonna go rob a bank now... and put some lotion on those dick beaters..... Ok, now that the comedy is out of the way...... You say you PH your water to 6.3-6.5... What you have going in, and what your soil (I assume) is buffering it at are two different things. See my post "Hard PH Corrections", and you'll see that even tho you may be feeding in at that, it may not be "Buffering" at that. You really need a good soil probe meter (a good one) to see whats really going on at the root zone. Slurry tests, and run off tests are really unreliable. If you're roots are really at lets say 5.5, then you're going to have nute uptake problems... I feed in at 1000ppm from clone to harvest, pedal to the metal, but I have them balanced out in the zone at 6.5-6.8.... run off will tell me differently when I test it. This is all assuming you're in soil.
PS... Im usually not a smart ass..... feeling spunky tonight. Keep up the good work bud!