Huh... I have not started adding flowering supplements waiting for the yellowing to be fixed, but it did begin after seeing pistils, so it makes sense. I'm using Mega Crop v1 with calmag and epsom... have some Bud Explosion as well ready to supply... pH always in check between 5.8-6.2 . Symptoms kinda come and go, but increasing the EC has proven helpfull. Will start PK supplement this week. Thanks.