Butterbudface, lets go back to the begging, it sure looks like overwatering. But as you say you are watering ever 3 days when the soil/coco is dry and have good drainage.. so maybe the cold temps have stopped the roots absorbing nutrients, salts dissolve better in warmer zones than colder ones so maybe that has something to do with it. MAYBE..
A few questions though,
Is it coco coir?
What is the ph you are feeding?
What are the 3 part nutrients you are using( brand)
It looks like all are clones, so the yellowing on the leaves that are cut on the smaller ones is fairly normal. But obviously the drooping is not.
Like I say, could be those real low temps that have shocked the root system, a bit like when they get transplant shock.
If you look it up they do seem to match the same sort of symptoms as over watering.
Also after looking further into it root bound veg plants would also wilt and yellow. But then the ones in hydro could not be root bound.
It all leads me to think that the root zone in both methods has dropped so low that the roots are either in shock or otherwise unable to absorb the nutrients and thus wilting and in the case of the larger ones feeding off the plant rather than the roots and yellowing.
This is speculation on my part and should be only used to further search and help solve the problem at hand.
Hopefully now you have got the temp situation back to a reasonable level they may perk up, in which case I would give them a good feeding and monitor their progress
