WTF, seedlings yellowing...

These guys are about a week from when I planted the seeds in a soil mix of ProMix with 10% perlite, %10 sand, and my friend who was helping me mixed in about %10 worm castings (when I wasn't in the room, forgot to tell him those didn't go into this grow, let alone with seedlings). They were fine till yesterday, now the vanes are yellowing and progressing outward. Please help, I hope it's not those fucking worm castings, but I never heard of those causing burn on even seedlings.... Thanks!

Ok so I just checked a growing video online I have had downloaded for a while... they use a soil with pre-mix for seedlings and that shit is far stronger than the worm castings, and usually contains higher amounts of amonial nitrogen so it can't be the worm castings in the soil. Any ideas guys?

It looks healthy in the pic man.
What type of lights are you using? If the spectrum is not correct they will yellow and die, but usually not this early. I would be checking PH as well. But like I said they do look good in the pic I do not see any abnormal discoloration.

Thanks, yeh I have them under a 400w HPS with a supplemental 100w CFL for blue light. I know blue light is best for vegging but my digital ballast is having BIG issues lighting Metal Halide bulbs... it has to go back to the manufacturer. I thought that you COULD veg under HPS even though it is not ideal , but I didn't know that it could cause seedling death if the spectrum isn't right. I have another 80w CFL, I will turn off the HPS, lower the 100w CFL and add the second 80w CFL. Guess I was just being lazy...pain in the ass to set that up lol

Ok done, I didn't think I had enough CFL for the space and plants but I found an extra 2, 23w cfls in my closet. They were beginning to stretch a bit, this should stop that.