alright...there is a good lesson for you...the 1st remedy of many when encountering plant problems...droopiness, always makes me laugh.
Cause...too much water/not enough water...lol

cause 2 too much light/heat, not enough light lol

cause and effect you needed more water, because you had built up salts...good job to flush. now fresh nutes at full strength in a few days, next rez change...should put you right on track

make sure your rez levels stay right up to the netpots. always use ph5.8 water to topoff in between full nutrient solution changeout's