I think they are hungry that is why they are drooping?? Everything I've read says that you go 1/4 strength after the 2nd set of leaves (not counting the starter leaf set) and thats what I did...no problems I had a funky looking white widow but its back on track. I dont know the feed scedule of your nutes but whatever it is for grow or veg cycle, just quater it and you should be good to go. keep the ph good and an air gap from your net pots to your water level (as long as the roots are touching the water), enviroment looks good, I kept the light about 16" away and once they get a little bigger you can keep it between 8-10 inches away as long as you have a fan blowing at canopy level. I checked mine this morning and the plant had grown to about 6 inches away with no problem (250 watt HPS). I hope this helps, give them a little snack and they might pick up, It'll be slow until 2-3 weeks after you started feeding them. Once you give them 1/4 strength keep an eye on them and you can give them a little more a few days later, keep track of your ppm and you can brign it back up after a few days, Then on your next change out add 1/2 strength and keep an eye on them a few days later add another dose of 1/4 strength and then on your next res change add 2/3 strength then a few days later add the other 1/3 and keep increasing what you start with at your res changes. Thats what I am doing and it seems to be working great. Keep your res changes to about 10 days or so.
Hope this helps...
remember when you add ph up or down it will increase your ppm.
For your nutes, are you supposed to use the grow and micro together? If so, you should at 1/4 strength...