Maspino,

I think you are using nutes way to early in growth IMO. I don't start mine until they come out of the seedling stage or first set of 5 finger leaves. There are plenty of nutes in the soil for seedlings.

Do you have any more seeds? I would be ready for a back up plan because you are basicaly doing an experiment and you will want your seedlings as healthy as possiable. I don't think you have a light problem, just a nute and watering issue going on right now that may affect somthing down the road, just my opinion.