Photo period when switching to MH

[DiverDude]

I'd try and get your lights higher up for a while. If that's not possible then the previously mentioned layers of screen should work in a pinch.If you raise them, drop them an inch or so every week until they are where you want to leave them.

Dropping an hour from your photoperiod may not be a bad idea either. However I certainly would not switch them on and off. Remember you are trying to simulate a slice of ocean in your house and in the wild, the sun does not pop up and down every few hours. Will it hurt the fish ? Probably not but I don't think it's good for the lights/bulbs.