I have 4- 600 watters and the best bulb that I have found to use is the Sylvania Gro-Lux and the Sunmaster. I used a light meter on both bulbs and they claim it produces 95,000 lumens with a magnetic ballast. The digital ballast will produce 112,000 lumens.They are all Future-Brite ballasts,120volts.They have saved me some money on the electric bill,too!Hope you get the most from whatever you choose to buy!

Ga Grown!