Adding 50-100 ppm, do u believe it should be potassium heavy, ie, GH bloom heavy? Or more equal amounts to add up to 50-100?
the lowers might still pull some n in and green up a bit, but yes they would move to a flower / bloom nute. they aren't that far from finish. idea is just to get them there as nice as possible. it doesn't have to be pretty. you have a good run going.
i wouldn't do just pk, they still need / use n in flower, and you're bringing them back a bit. i never ever run a booster alone, and i don't usually run a booster at full strength. i make some head room in the regular nute sched and add it in.
if base nutes can't do a decent job alone, then drop the line entirely.
Bluter will give you more cogent advice soon, let's hope. Until then, the screenshot here shows the amounts of chemicals that are some of the GH products. If you scan across the line for "K", you'll see how many PPM of K are in a given fert. Not a lot, eh? Adding even 50PPM worth of K could cause a serious imbalance, AKA "lockout".
One warning - I don't think there's any evidence that "bloom nutes" actually do anything for cannabis. You might check out this thread for a perspective on that. Full disclosure - I've drunk the Koolaid. I uses dry ferts, same mixture from seed to chop.
holy shit. i don't think i'll ever be more cogent than that chart.