There is a particular ballast you need, at home depot. Advance REL-4P32-SC, $18. It can run from 1 to 4 32 watt bulbs. You trick it into thinking it is running 4 bulbs by running all connections to one bulb, so one bulb gets 128 watts. You can use any 4 foot bulb, I use T12 because they are cheap. At 128 watts the bulb will run a little hotter, but double the lumens. Of course there is some loss via heat, that is why you will only see double. Bulb life will be cut in half. You can also run 2 bulbs at 64 watts a peice, for something like a 25% increase. I will post some pics of my ballasts later today in my journal. The heat increase is nominal, my baby plants are only 4inches away and loving it. Feel free to ask more questions, Biffdoggie knows about doing this too.