What is the Best Reef Tank Lighting Schedule?

Categories: Lighting, Guides & How-Tos, Saltwater

Author: Adam Monte

Last updated: Mar 25, 2024

Creating the perfect lighting schedule for your reef aquarium is both an art and a science. It's about finding that sweet spot where the light mimics the natural conditions of the ocean. While there's no 100% correct answer to which lighting schedule is best, we've come up with three rules of thumb to get your reef tank started off on the right foot.

1. Pick a Proven Spectrum

We use light fixtures over our reef aquariums because most corals depend on their symbiotic relationship with photosynthetic algae known as zooxanthellae to survive and grow. These microscopic algae reside within the coral's tissues, converting sunlight into energy. But the type of light we provide our corals matters! We aim to mimic the natural light conditions found in the coral's ocean habitat, particularly emphasizing the blue spectrum that supports optimal photosynthesis.

Many light manufactures have pre-sets built in, which are specifically set up to do just that. For example, EcoTech Radion lights have their AB+ spectrum, which is the result of extensive testing of coral growth and coloration. Other lighting fixtures like Kessil also have built-in settings that make choosing the right spectrum a breeze. If your light fixture doesn't have built-in presets, we usually recommend setting the blue channels to max, then work in the white channels to make the tank look visually appealing.

2. Use the 1-8-1 Ratio

What is the 1-8-1 ratio, you might ask? 1-8-1 means 1 hour of ramp up at the beginning of the photoperiod, 8 hours of steady intensity throughout the day, then 1 hour of ramp down at the end of the day. This give you a 10-hour lighting schedule, which is right in the middle of the typical 8-12 hours that most hobbyists recommend. Of course, you can set this 10-hour period to start when you're most typically home, so you can get the maximum amount of viewing time and enjoyment from your reef tank.

3. Pick the Right Intensity for your Corals

In a reef tank, finding the right balance of light intensity is critical because both extremes—too low and too high—can harm the corals. Too little light often leads to the slow decline and death of corals, as their symbiotic algae, zooxanthellae, fail to perform photosynthesis efficiently. This means the corals don't get enough nutrients to survive. On the flip side, too much light can cause coral bleaching. This usually happens more quickly as the intense light can cause the coral to expel the zooxanthellae, which causes the loss of color.

The best way to measure light intensity in our aquariums is to use a PAR meter, which measures photosynthetic active radiation. If you don't have access to a PAR meter, it's always better to start off at a lower intensity and slowly increase it over time to let the corals adjust.