How would you switch over from VHO to MH?

[Andy]

In about a week, I will be receiving all of the components for a MH/VHO lighting setup. I will be running three 400 watt radiums and two VHO actinics over my 280 reef. For the last year, I've been running with six 5' VHOs and a single 4' NO actinic. Obviously, the new lighting will be significantly more intense than what I am currently running. Many of the corals I have, have been under VHO for the last 5 years or so. How would you go about the transition from one to another. Would you switch over to the new lighting system completely or run both lighting setups for a period of time slowly increasing the MH lighting period and decreasing the VHO lighting period. I am in a position where I can run both. I have heard some people say that they put some light diffuser between the MH and tank to reduce the intensity during the transition period. I have also read of people bleaching their sps during a VHO/MH transition. Any comments or thoughts as to how you would proceed.

Thanks,

Andy