Do I need to acclimate my new lights?

[gcfiend]

I'm currently running 2X 250W 10K MH in my 90 gallon. I bought ballast and bulbs used and recently noticed signs that the bulbs may be a little old.

I ordered and will be getting 2 new XM 10K today. Can I just install, or do I have to get eggrate or something to diffuse the new light for awhile?

What are some signs that the light is too much for my corals? I have mostly SPS on top and zoos on bottom. Couple of LPS in middle and bottom as well.

Just wondering from the group if others just install the bulbs and not worry about new bulb acclimation?

Thanks in advance.

[gh0st]

It's not a bad idea to cut back your photoperiod a bit when changing out old bulbs. Some times the new bulbs are so much brighter it can induce bleaching in the corals.

Alot also depends on how old the bulbs you will be replacing are. If they are really old and dim, cut back a couple of hours a day with the new bulbs and increase the time they are on by an hour or so each month until back at your normal photoperiod.

Or just raise the fixture a bit higher of the surface, and gradually lower it over the same time frame.