2 things. Yes, get the light closer, probably 6" would be fine for a 150 MH. Second thing, start them on 1/4 concentration nutes soon and work your way to 1/2 strength in a week or two depending on how they do. If you want to be overly cautious, start em at 1/8th.

This is not soil, when the seed runs out of pop you are gonna see it drop.