Pineapple Express Auto BARNEYS FARM

as with my other plant this one has some symptoms after my flush last week. would i be right in thinking its cal mag it needs, has brown spots and leaf edges are yellowing. also installed a new light which may have brought these out more as have doubled my power. gave a dose of cal mag so hopefully they be ok in couple days. i believe my ph is correct after calibrating 2 pens and both reading 6.3 in soil run off.also the stems at the top of the main colas have purple stripping to them is this from stress? leaves also droop slightly which my other plant doesn't is this a concern? don't think its over watering as they are dry before re feeding. they seemed slow this week as they've stopped there stretch and putting more bud mass on. she's really big tho manged to lst her to the space a bit better and fill half my tent with her.. any help out there? should i change anything? any advice?