They are on timers.
My issue is, the fixture is an old single ended socket type.
If there is a short power outage. The fixture tries to start back up, and never really comes on.
So I would rather be safe than sorry.
I will leave it off regardless (the house behind mine, burned to the ground 2 weeks ago) I was just curious if it would have any ill effects on the corals
5 days wont have any ill effects on your corals. people leave their lights off for about that amount of time when they get cyano break outs. you should be fine
I recently came back from Vacation total of 14 days and did not light my Ce 250w but I did use the actinic and plug the MH out fill the auto top of and ask a friend to keep an eye on he top off water level and also I did not do any feeding of the tank.I left 10g of made up water just Incas.I think if you turn off the MH it will be OK.