that is nute burn...whenever you see tips burning up...your nute s trenght is too high. bad ph can lead to similar problem, but you wouoldn't see the burnt tips. you could've just flushed with ph6.5 water 3x the amount of the pot. i.e. 1 gallon=flush with 3 gallons

personally. I think you ar ein a dangerous area, and better watch them closely.

To accurately check ph from a potted plant...water thoroughly, then check the runoff after 10-15 minutes. I have never had to adjust my water much for soil plants. I also do not believe that miracle gro potting soil ph is way off. If that were true, no-one would be able to grow anything with miracle gro; and although I wouldn't grow pot in miracle gro soil...that just isn't so. peace