We strongly recommend you run your lights on a timer(s). The plug-and-play kits we described above sometimes come with an integral timer, or they ship with external timers. If your lights don’t come with timers, get them. An alternative is to use an aquarium controller to control your lights. However you do it, you will want to have your lights on between 12 and 14 hours per day.
If you use a combination of lights, you could program your actinics to come on for an hour or so before the full spectrum fluorescents or metal halides come on, and then have the full spectrum fluorescents or metal halides go off about an hour before the actinics go off. In this way, you mimic dawn and dusk. If you have LED
lunar lights, you can also set these up to simply come on at night or to mimic the phases of the moon. Regardless of how you set up your system, remember that lighting is critical, and so is consistency from day to day.
The best advice for a beginner aquarium keeper is to spend good money on lights; and don’t be surprised if your lights are the single most expensive piece of equipment you purchase for your saltwater aquarium—they are that important. Good luck!
From The Complete Idiot’s Guide to Saltwater Aquariums by Mark W. Martin and Ret Talbot