... looks like P defc. is kicking in, likely lack-of,.. the color burnishing is a symptom, unless your plant is getting cool nights? NLx BB may get some color, but it's not a known purple strain,... the large necrotic spots are P defc., and the yellowing could be N and/or P combo,... are those leaves from the lower parts of the plant? mid-tops, further yellowing,... P related, might be S kicking in now too,.. often overlooked, S is a econdary nute, and the plant needs significant amounts of it,.. I don't see anything in you inputs that covers this,.... epsoms is a good choice- MgSO4, 1tsp/qt,... feed more JT! What's the NPK#'s on the bat poo?