I just built a 6ft high by 4.5x2.5ft growbox in my outside greenhouse( greenhouse gets too cold to use it in the winter. I was wondering if I can skip using the fluorescent lights for veg and just start off with the 400w HPS for the entire grow. Also do you think that the intake vent at 1.5 inches pvc and 4 inch out take with fan is sufficient? Thanks!!!