The Proper Lighting Time for Reef Systems

As you start out a new reef system or even begin tweaking an established one, consider that proper lighting is required for optimum aquarium health and coral growth. In addition to basic coral growth, algae use photosynthesis to grow during daylight hours, adding oxygen to the water.

  1. Lighting Duration Guidelines

    • The overall goal of lighting a reef aquarium is quite a bit different from lighting a fish-only aquarium. The primary purpose of lighting a fish-only aquarium is to help the fish recognize a difference between night and day and to help you see your fish better. The primary purpose of lighting a reef aquarium is to support coral growth and health. Too much or too little light can have deadly consequences.

      Guidelines for aquarium reef lighting ranges widely. An article in Aquarium Fish Magazine recommends from five to eight hours of daylight a day, and WetWebMedia recommends between 12 and 16 hours of daylight a day. This is a pretty broad range, so one method of choosing is to pick a middle ground of 12 hours of daylight to start with. This splits a 24-hour period evenly between day and night. Watch your aquarium closely, and after several days, if you see any ill effects, increase or decrease the amount of time the lights are on.

    Simulating Biorhythms

    • You can use lighting to simulate the natural rhythms of day and night. You can accomplish this through multi-switch timers that create a gradual change in lighting from your primary day time lights to your night time lights. Night time lights, also called lunar lights, provide a diffuse night time light that simulates the moon. Using lunar lights means that your aquarium is never completely dark, which is a more natural environment. You can also use lunar lights intermittently during the day to simulate cloudy days.

    Longer Daylight

    • Reasons you might need longer day light hours include: light-loving coral, lightbulbs getting old and not putting out as much light, and coral are regions that have longer daylight hours

    Shorter Daylight

    • Reasons you might need shorter day light hours if you have metal halides but don't have any high-requirement corals, you have switched from a less-intense light to a more-intense light, you have swapped out old bulbs for new ones, or your coral are from regions that have shorter daylight hours.