I have a 400W CMH that runs off a magnetic HPS ballast. Both me and the plants really like it. They don't make them anymore unfortunately but GE has one with the same specs I believe. I got so many bulbs now that I shouldn't need any more for the rest of my life. Mostly using EYE Hortilux 600W SHPS for flowering. Never did get a 315.I wanna know more. I love my CMH. Are they 315 watt's too? And when do you run them?