Not all plants respond the same to nutrients, that's one thing about folks who've been running the same strain for ever have an advantage with. Yeah, that's super concentrated stuff - their website says to use a "a few drops per gallon" so I'm going to go out on a limb here and say 0.5mL per L was too much. Something in it (Vitamin B especially, like superthrive) could increase the uptake of certain nutrients perhaps? I'm not entirely sure - I'm not too fond of nutrients that don't tell you what's in them or what's going on. I, much like Darwin recommends, would not worry about the Jack all too much yet. I'd give it a bit more time and see what happens.. just follow along on your nutrient program.. Has vertical growth stopped? I would not introduce bloom nutes 100% until vertical growth stops? What all will you be using for bloom, just Oldtimers? I'm confused by this as you said you were running Ionic nutes.. you mean you were only running their grow fert?