Mg deficiency?

So I'm going to disagree with my growmies about the pH... 6.0 in soil is perfectly fine and all nutes SHOULD be able to be absorbed... I tried to find the NPK numbers for the Dr. J stuff and was not successful... And you're not making sense to me when you say you're now feeding with "FF Sensi Grow - Bloom" since Sensi is Advanced Nutrients, not Fox Farm... BUT... I think that your issue is probably one of a lockout of calcium and magnesium due to an overload of nitrogen... I know that Sensi Part A has an NPK of 4-0-0 which is crazy for flower... and I'm highly suspicious that the Dr.J stuff, since it screams it grows great big stuff, probably has a very high level of nitrogen as well... So here's what I would do: flush. Flush, flush, flush... get everything back to basics, ground zero so to speak... run 15 gallons of pH'd water through each pot (the general rule of thumb is to run 3x the amount of water as your pot size) ... into the LAST gallon of water, add your bloom nutes only... then let them dry out before continuing on with your water/feed/water/feed routine. The damaged leaves are not going to repair themselves, so don't expect that... but you shouldn't see further progression of the problem. Good luck!