i actually use a 0-50-0 bloom boost at wk 4, i normally dont notice a need to boost K, in rockwool, but if i was in coco i would as K strips in coco as well
i use rockwool so the bloom booster i use is Bud Boost from Green Planet Nutrients, salts that need to be mixed and smell kinda like vegemite
what week are you in, what are the genetics