Hey guys. I'm considering buying a 400watt grow system with a dimmable ballast: http://www.amazon.com/gp/aw/d/B004YXDHX6/ref=mp_s_a_1_1?qid=1368778249&sr=8-1&pi=SL75 I'm trying to use 200watts now, but have the option on hand to use 400watts if needed. Does running the ballast on 50% actually only use 200watts? Or am I still using the same amount of energy (400watts), just dimming the light spectrum? I'm asking because this is my first indoor grow and I have 2 plants vegging now under cfls, and If this first grow goes good under 200 watts, I'm going to up my wattage next time to 400 watts, and it would be clutch if I can just turn a knob instead of buying a whole new system. Thanks guys