New ballast on M.H. light causes bleaching

[fencer]

I always thought electronic ballasts correctly "drives" bulb output. Maybe what you are seeing is the correct color for the bulbs. If the ballast is not working correctly...it might be overdriving the bulbs...

[KPG007]

Raise the lights for a week or so, then, over the course of a couple weeks, slowly lower it to your prefered hieght. that allows the corals to acclimate to the new light conditions.
As for the corals that are bleaching, as long as they are not dead, they will color back up (although this may take months depending on the severity of the bleaching).

Kelly

[Madreefer]

I just changed my bulbs and had a little bit of bleaching. After I noticed it I shut my lights off for a day and cut the mh schedule in half and have been slowly uping the time each day. Has'nt gotten any worse and the coral actually is starting to look better.