Big Chillin, is that 34 " below light? 34-14=20" your at 9" now, are the nodes alternating? Meaning are the fan leaves forming across from each other?, that gives you 11" stretch available (50%)when you flip to 12/12, its a little tight for that size box. I 'd agree and say yes flip now, but because your box is so small that 400watter will create other problems such as heat, Do you have a good fan? A good size box for a 400hps is 30 x 30 x 70, or if I redid mine I'd make it 48"wide x 36 deep. I too am a soil grower. Moving from Floro's to HPS changes light spectrum and light intensity which produce hard buds. We can provide further advice, so a couple more Q's, total dimensions of box, how many plants? how tall is your light with hangers. You have options, you can top to promote side growth, thus decreasing your height, pinch which also promotes side growth, but that will not decrease height just double your colas, so energy of plant is shared between two smaller cola's.
What strain?
