did you try dropping the nutes in order to not raise ec when you added booster or raising it only a little. for instance i think dansbud said he dropped his nutes to .8 ec and raised it 1.4 with with boosters.
I ran only the 3 part on their schedule for almost 10 years in soil. Good stuff and easy. Only problem was I succumbed to the hype and tried to add koolbloom powder and others in bloom. No matter how weak a dose I used I always burned them some. Had the best buds when I didn't mess with the powdered bloom additives. But that was soil