[stephane]

As strange at it is I have read somewere that the regular ballast is harder on the bulb I tink because voltage is to low but this need to be verified

The HQI ballast have a voltage of 200 volt and the radium spec said that this bulb should be run on 230 volt but the difference probably is the amp
on them

If my memory is good MH ballast are 95 volt ballast but hight amps so it match the same wattage but different volt

I dont know a lot about ballast I know that oldreefer and paulerick on RC know them well maybe we should ask them

If you have a mutimeter I would be curious what voltage are on the bulb out of you regular ballast + what Amps it draw on the 110v.

Ho and dont forget that this bulb need to be break before give good lightning most of the new user complain about the brightness the first 2 week on HQI ballast