I personally use LED lights for my refugium and keep them on for about 10-12 hours a day. I find that this schedule works well for the macroalgae and other beneficial organisms in the refugium. However, I know that some people prefer to keep their refugium lights on 24/7. Ultimately, it depends on what works best for your specific setup and the organisms you are trying to cultivate in your refugium. Thanks for asking, Gilbert!