Before I start an argument or anything like the sort, please check out my grow. I am using pretty much the same setup and bro those seedlings look burnt. I hope your not using Miracle Grow, that crap is so high in salts and just are too much for MJ. They cause nutrient lock up and burn plants easily. I think it would be best to go with the chems that came with your kit. They are working awesome for me and all I have is a 150 watt HPS, not a nice 400 like you.
We are planning on getting one before bloom and we are gonna do a scrog very soon also, before bud
Nothing leads to good that is not natural - Friedrich Schiller