I used one cool and one warm flourescent bulb in each light fixture. In your case, two cool and two warm if should be on the light bulb box. I wondering if you might of over watered.
I only bottom water the plants. I put them in under the bed plastic totes and water them so that the water fertilizer mixture (do not add fertilizer to the water until they germinate) can be drawn up from the bottom. In addition, I usual chamomile tea in the mixture to help ward off damping off and I also put a little sand on top of the soil in each pot. Doing it this way keeps down on the fungus nats and keeps me from over watering.
In addition, I turn on a fan once or twice a day it strength the stems. You can also do this by blowing on them or lightly running your CLEAN hands over them. I do not rise the fixture more than two inches above them ever. Most important thing, ONLY USE SOIL LESS MIXTURE...using potting soil will make your life a living hell if you use it....to many pathogens in it to start
seeds. I love Pro Mix by Premier. If you can find use it. Nice, light, and very clean.