Your fish might be getting stressed out from the sudden light change. I've noticed black skirt tetras getting pale before when I'm working on a tank or if something scares them. You might want to decrease the light level and let the fish slowly get used to brighter light over a period of days. If possible, you can keep the light higher up over the tank, or put some kind of barrier between the light and the tank. If your tank has a built in hood it might be a bit difficult though. They should get used to the brighter lights within a few weeks though, so it shouldn't be a permanent issue. One thing to consider would be having a second, dimmer light on a different circuit, such as a desk lamp or something. Turn the second light on maybe a half hour or so before the main light, so the fish will get more of a gradual light change instead of an abrupt brightness that they aren't used to. I have a dome reflector with two spiral fluorescent bulbs for a morning and evening light on my 50 gallon tank. The main light is 2 fluorescent tubes on a reflector hanging over the tank (I don't have a hood on my tank). I have both fixtures set on timers, so the less intense dome reflector lights go on an hour or so before the main lights, and turn off an hour or so after the main fixture does.
Consider giving your fish more hiding places, such as a denser area of plants if you don't already. They should get used to the new light eventually, so don't worry about it too much yet. If they're still getting stressed out a week or two from now, it might be a good idea to try a less intense light bulb.
Good luck!