I'm getting a new ballast. Going from 400 watt to 600 watts dimmable. I want to veg under 400, then flower under 600. My new ballast is dimmable, so can I use my current 400 watt mh bulb in a 600 watt ballast dimmed to 400, or do I need a 600 watt mh bulb, which itself would be dimmed to 400? Thanks.