Way to complicated guys. That plant is in a pot thats entirely too small. I bet it's root bound and has used up most of the nutrients in that bag. Transplant and it'll be fine
I agree with Blue Cloud. Before messing with npk repot in 20 gallon/min fabric container. Let the nutrients from new soil do its thing. Don't expect next day results. Also, top those ladies.
You're cooking their roots in those black pots and bags. And your coco looks dried out. Get that in check before you adjust your feeding regiment. You don't have russet mites.