Switching to distilled water in the middle of the veg growth may have contributed to discoloration. You basically went from using tap water that has various minerals in it, to a sterile water source after the plant had been acclimated to the tap water since a seedling. I've read many articles on tap vs distilled, and if you're ppm levels are good in your tap water, I would def use that over distilled water, plus... save money. The initial shock could have caused discoloration. Wouldn't change back to tap now, but food for thought for your next grow. This may not be the cause, but there are lots of discussions online that you may want to check out. Best of luck to you!!
likes 2