Looks to me like she is thirsty and a bit of a finicky strain, never grown it myself so have no idea, how often do you feed and how often do you water? do you find she goes through more than the others, needs more frequent waterings? im with BF on the flush, give her a good flush with water, give her a day or so to dry out a bit, when she is ready give her a new fresh feed and should perk right back up
could be that she just needs a few waterings between feedings or a heavier watering at feed time, i find in warmer conditions with my DWC systems (i know its a different system but a plants a plant
) they will drink a lot more water leaving a stronger ec/ppm in the reservoir, if i was to top this up each day with my nute mix by the end of the week my ec/ppm would be triple what i started with, however, in cooler conditions i find the complete opposite
what im noticing with these LEC lights is the plants drink a lot more and keep the temperatures warmer at canopy level, have given one of my girls over 23L of water in the past 4 days