Check this thread
http://boards.cannabis.com/indoor-lighting/133316-ceramic-metal-halide-bulbs-hps-ballasts-3.html

Maybe helps
tevfik Reviewed by tevfik on . Quick Question about MH/HPS , Please help guys Just wondering what would be more benificial for vegging my ladys , either a 400 Watt MH or a 600 Watt HPS ?? I know that they like MH for veg , just wondering if the other 200 Watts id be putting out , even though mostly the red spectrum ... would be better than the 400 W MH . Thanks for any help Rating: 5