Its not nute burn mate, nute burn starts from the edges of the leaves. Heat damage start by the leaf edges curling up, which is exactly what some are doing but really bad. That halogen light no good serious.
Also dont water when the light is on it will magnify and burn them. You need to re pot into some good soil mix, only grow as many as you can fit in the room and get some more cfl's. Blue spec for veg 6700k, red for flower 2700k.
That halogen killing them. some will find it hard to pull out of this. Get better lights and maybe think about starting over with a bit more knowledge to start and a half decent set up at least. sorry to say that man but it's all learning. But get new lights defo.