CFL bulbs have their own ballasts, built-in. I wouldn't screw it into a 400 watt HID ballast fixture.
Dutch Pimp Reviewed by Dutch Pimp on . CFL bulbs Hey guys, I've done a bit of searching but am unable to answer my question. I currently have a 400W Sonlight HPS Agro bulb with ballast. I was wondering if I would be able to put a 250W CFL in there instead for my veg period. I am aware that the Agro bulbs give off a bit of blue light for growth, but it's mainly to manage the temps and I don't want to blast seedlings with the HPS. Thanks. Rating: 5