I am not sure if I understand your question. But if you are asking whether or not, you should turn your lights to your fuge off, when you turn main display off, the answer is no. You should do it in reverse. Main lights of, refuge lights on. That will stop your PH swings at night time. Now it is a big debate about the 24/7 issue. Some say it is best to do it 24/7 some disagree. I have read that some people say it helps stop caulurpa from going a sexual. But i do not know enough to agree or disagree with that. I do no that it should at least be ran opposite of tank lights. HTH