Seedling turning brown

Hi again, my friend has gerninated and planted some Super Skunk and Royal Cheese seeds. Some are up about 3-4ins and were looking healthy on a 125and a 80cfl. Lately the leaves have been going brown or going a lighter shade of green and looking very sick. I went over and I have changed the compost and even put small fans in the room but they are still not looking very good. They haveny got dry or over watered. I havent seen this before as I use clones not seeds. Any help please. I enclose a photo, moe here if needed

What kind of soil? Have you been feeding them?

Looks like nute burn. Flush with clean water ph 6.5

Compost? That stuff might be too hot for those seedlings.