That plant is going to be so fucking huge after the 12/12 stretch... hope you have a good 6' of height space.
Sorry, not sure what's going on with your leaves... ph, ppm, and ambient temps are fine. You can try moving your fan or pointing it at the wall, but I don't think that's the problem. If your ph is dropping significantly, or roots are turning brown or slimy, it could be a sign of rootzone probs, but you don't mention anything like that, so hard to say. I'm not good at identifying deficiencies, maybe someone else will have a better idea. My problems have always been cause by ph, water pathogens, or high ambient temps.
When in doubt, gently/carefully rinse/flush out the roots and make a new res. If you think you may have pathogens in the res, use a small amount of sterilizing agent like chlorine (tap water), h202, bleach, etc.... then start using benes if you aren't already. If you aren't having root problems, you can probably ignore all this shit.