Barneys blue cheese, purple stem spots on leaves..?

I have barneys blue cheese. Just one under a 400w hps, veg egged under metal halight.. Using all canna range, and canna pro plus soil.. I know the cheese is peculiar with nutes so the build up has been slow..
So I am 4 weeks into flower, I have a ten litre can(or 2 gallons or there abouts), and the nutes are as follows..

Cannzym, 1.1/4ml.
Boost. , 2.3/4ml
Flora. , 2. 3/4ml. ( I know quater and half ml, is a little over the top, I don't want to make a fuck up..)

The next feed will be, pk..

Should I increase all my other nutes as well as a dose of pk ?
Every time I have grown before I have been gettin purple stems ? Anyone have any ideas?. Thanks

Pkis why the stems are purple. I like purple stems. What kind of spots or what color spots?

id say just flush it and wait for results purple stem might be PK has haloman420 said but might also be PH def. not sure though but you should flush her and wait to see if any greeens ome backup I think it might be your solution