RE: Metal Halide Ballast
http://www.reeflightinginfo.arvixe.com Look here and you can compare the lamp and ballast combos to see what works the best. Electronic ballast don't over run the bulb as much as HQI ballast but if you go 250 DE on HQI ballst you can get about 325 or so out of a 250w bulb. So you might not have to go all the way up to 400w. DE bulbs are designed to be run on the HQI ballast and from what I can tell don't have premature life due to being overdriven by the ballast. One other thing isthe e-ballast tend to make the bulbs a bit bluer then mag ballasts. here are a few more threads that might help as well. http://www.reefcentral.com/forums/sh...hreadid=201570
http://www.reefcentral.com/forums/sh...hreadid=575417
HTH.
Doug
Fightin\' Texas Aggie class of \'98