The only metal halide you will find in 600w is a "conversion bulb". I don't know why, but 600w straight metal halide doesn't exist. You have to get a special bulb that's designed to burn halides but operates in an HPS ballast. Hope this is what you are looking for.
irydyum Reviewed by irydyum on . 600 watt Dual Digital Ballast lighting question Hi all! I've been researching my grow setup for sometime and I have stumbled upon a small snag I haven't seen addressed in this forum. As of now my setup will include 2x 600 watt Metal Halide/Hight Pressure Sodium lights using 2x Lumatek 600 watt dual digital ballasts. These ballasts can go down to 400 watts. I'd like to use 2x 600 watt MH bulbs for vegetative growth initially but 1) I don't seem to see many 600 watt MH bulbs available for some reason and 2) have seen that some Rating: 5