If you have a DE set up and want to run your 250w SE bulbs on the HQI ballast you will overdrive the bulbs and get actually more PAR from them. They will have a max life of about 6-8 months. This is a good choice IMO though.
I have replaced 5 DE bulbs in my light in the last year. Not because of bulb life or ballast problems but because the sockets for DE are absolute garbage. I have talked to more than one manufacturer about the problem and they all say it happens. In my fixture, the replacement sockets are made of thicker gauge wiring and metal and are nickel coated vs. being copper. To date, these bad sockets cost me close to an additional $400.
My lamp is an Aqua-Medic Sexy series with 5 MH lamps(72"). I am not impressed at all.
I believe if there is a problem with the sockets then they should of sent a full set of replacements and not one at a time at my costs. Total Crap! I guess just keep burning lamps and replacing sockets as I go.
One other thing to note is that DE lamps will not produce the same color as an equivalent lamp(250w Se vs. 250w DE) by the same manufacturer. It just doesn't work that way. Mogul fitted SE lamps burn truer and produce just as much par as the HQI lamps. The color IMO is definitely better with the SE lamps.
