Yellowing during flowering ?

[BROMAN]

I'm 36 days from the flip. Should there be much yellowing ? Both my stains (cotton candy, stawberry blue) are, particularly in the middle directly under the light. I've also got some browning edges, tips and spots(cc). I consulted mj garden saver and chalked up thebrowning to a pk deficiency. To be safe I semi flushed with ph'd water since every symptom can point to 2 or more problems.. I'm using canna coco and the rest of the lineup. Growing in Mass Producer's coco buckets. Sorry not pic capable .