i've put 6 ml per gallon into a plant that was healthy, and it fucking killed it...it ate all the rootlets and left only the large "cable" roots, which are incapable of supporting a large healthy plant.
you can say whatever you want, but i'm never using over 3 ml per gallon of anything over 30%....and have absolutely no reason to, that seems to be entirely strong enough to keep my hempy bucket resses sterile and fresh smelling. using more would be both a waste and bad for the plants.