when you give them 1-2 weeks of distelled water they have a chance to build a nice root structure that enables them to uptake the nutrients, you would be amazed how good seedlings can grow the first two weeks with just distelled water, you dont even have to mess with ph that way. just keep temps of res in check and all is well.
does your ph drop everyday? if the answer is yes they are locked out, clean ur res then after 5-7 days of disteled water start the 1/8 mix they will spring back to life.
your aero set up should make them grow like hell..
ur on the right track man, just a slight bump in the road. hydro is great once you get to know it and it also can go to shit quick so stay on your ph 5.8-6.0
is safe 5.8 optimal.. hope this helps buddy i love hydro and would try to help anyone learning it