lights and timers

[kwtowmaster]

how many hours should my reef tank have the lights on a day ?

[EMS503]

I have my PC lights come on at 11:30 am and off at 11:30 pm,
MH come on 12 noon and off at 11:00pm.
All seem very happy with this combination, I also have a 15 gallon Refugium on reverse cycle to maintain pH and control nusiance algae among other things.
I would say 10 - 12 hours will be enough lighting time.