BROWN tip

hello all... 1 of my roomates 2 plants is browning on the very first set of leaves. only on one of the first set is browning, its browning in the middle of the leaf too if that means anything. It is smaller than the other one which is doing fine and thier both in the same size pots, lights, cycles, everything is the same except for the size and the fact that it is browning, any thoughts???

how hot does the room get?

Im not sure how hot it is but I just added 2 more 150watt (42watt) cfl's so now I have two on each plant and the surrounding area feels pretty warm now, I should probably get something to test the temperater and humidity..Also, I need to install a fan and a carbon filter on top for the smell. here is a picture of the box I just built.. The bottom is for germination and seedling/veg. The top two plants are veging and about 6 weeks now, theyre taking a long time but theyre green and getting nice.

I just found brown on the small braches on top of the fine hair. Its not grains of dirt but I think I over nutritioned it so imma give it water for a few times before giving it any more nuts...Also I just transplanted from Miracle grow to Fox Farm so hopefully that will help.

Any thoughts more on the browning?

yeah, miracle grow is not good. if the brown is around leaf edges then you're right about the nute burn.