I don't know if it's the lighting or not, but it looks a little on the yellow side. It may just be recovering, or still have a problem. Did you get the right kind of pH drops yet? Now that the seedlings are getting bigger, I would probably up the
nutrients to about 2/3 to 3/4 strength. They should start growing quickly if their getting enough light.
Also, I was looking for new articles today when I came across these three that I think you may find useful.
Control Yourself: Understanding the Basics of Indoor Climate Control
What’s the Problem? Hydroponic Troubleshooting
Cultivating Cucumbers
P.S.
Bigdaddy216, did you get the e-mail I sent you. If not, I can re-send it..