By straight flush do you mean rinsing the roots with fresh water and then filling up bucket with plain water or 200-400 ppm? Is that PPM x 500 EC or PPM x 700 EC? I check my pH basically everyday.Hey man. I would go with Sutragrow. This looks to me like they are just burning up rather than a defiency. I would cut back on the nutes. And do a straight flush. Run her on straight water for a few days. Or keep ppm real low like 200 to 400. See if you see any improvements. I would also triple check your ph. That is normally a really easy mistake to make. GOOD LUCK. STAY HIGH!!
That is the best thing you could have done. At least you will know now if it is a nute burn because it should subside if it was. If your problem stays occurring during this next week I would move onto thinking you have a deficiency. Any ways sounds to me like you are on the right track keep it up. STAY HIGH!!!Well, I dumped my buckets and made new solutions at EC of 1.2. Also i washed my roots with fresh water... hope it helps.