Shouldn`t need a lot of nutes at this stage, I`ve heard foliar spray with seaweed product can work wonders but I`ve never tried it myself. I`m usually waiting for the flowering cab to be freed up so I`m not in a mega rush for vegging.
Can be good to give them a few feeds to acclimatize them to nutes before flowering.
Maybe the heavy watering is stopping oxygen getting to the roots? I`d try a lighter watering in the first instance, if they have to work a little for their water it seems to encourage growth (especially of roots). Anyways they don`t need that much water until they get older and bigger.
Have you considered setting up a second space for flowering? Maybe get a MH bulb for vegging under the 400watter and using the big lamp for flowering.
P.S. Just my 2 cents Ἰησοῦς man, I know it takes a certain courage to subject ones grow to the gaze of the unwashed.
