Is White Light Good For Corals? Can They Grow In It?

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Most aquarists know that blue light is the ideal choice for corals. But not everyone likes it or how their reef tank looks in it.

This automatically raises a question that I have personally asked myself countless times in the past: Can we just use white light in a tank containing corals?

In this article, I’ll answer that question from A to Z, and provide some great tips I’ve picked up over the years regarding this topic.

Let’s dive right into it.

**Coral illuminated with white light on a blue background**

Is White Light Good For Corals?

Yes, white light is good for corals as it contains all wavelengths of the visible spectrum, including blue and red, which can promote coral growth. While blue light is still the superior option, some coral species in nature grow in white light.

Your biggest concern is the reaction from the zooxanthellae, the algae in the coral’s tissue.

Unlike the coral, which is an animal, zooxanthellae photosynthesize. They need light to thrive and survive.

However, the chlorophyll in zooxanthellae tends to discriminate. It absorbs specific light spectrums more effectively than others.

In particular, chlorophyll A in corals has absorption peaks at 440nm, and 675nm (wavelength),^[1] which explains the significant impact violet and red light have on coral growth.

Blue light is especially beneficial to corals. The color has shorter wavelengths (450 – 495nm), which fits into the range chlorophyll A absorbs.

It stimulates calcification, a process that allows corals to create calcium-rich skeletons.

Flooding an aquarium with blue light allows zooxanthellae to generate vital nutrients for the corals. In turn, the corals protect the zooxanthellae.

Does this mean white light is useless to corals?

Well, you can’t make that argument because some aquarists combine blue and white lights in their reef tanks.

The blue light benefits the corals, while the white light allows the aquarist to see the tank’s contents.

After all, blue is a dimmer color than white. It can’t provide the same visibility.

But what if you replace blue or blue/white lights with white LEDs? Would the corals survive? Yes, they would. Consider the following:

1. White Light Contains Colors Beneficial To Corals

First, this idea that corals only respond to photosynthetic radiation within the 420 to 675nm range is wrong.

Corals have other pigments besides Chlorophyll A, and C. Those other pigments use the entire visible spectrum.

Modern experts emphasize blue lighting because the color has a significant impact on coral growth. But that doesn’t make the other colors useless.

Even if you believe that corals require blue and violet to thrive, white light has all wavelengths of the visible spectrum, including blue and red.^[2]

It looks like one color. But in truth, white light is comparable to a rainbow. Therefore, a white LED will meet your aquarium’s demands for blue and violet.

**A complete reef tank under white light**

2. Some Corals In Nature Grow In White Light

Daylight bulbs, which generate white light, mimic the sun. This matters because corals in the wild survive and even thrive in sunlight.

Aquarists emphasize blue because many coral species occupy the deepest sections of the ocean.

The water filters the sun’s rays, absorbing the colors with the longest wavelengths. This is why many aquarists do not use colors like red, orange, and green in their coral tank.

Only blue can penetrate to the lowest depths. For that reason, corals on the ocean floor have evolved to photosynthesize with blue light.

Unfortunately, many aquarists make the mistake of assuming that every coral species originates from the ocean floor.

They don’t realize that some species live in clear, shallow waters where the full spectrum of the sun’s rays can reach them.

These coral polyps have a transparent construction that allows the colors of the algae beneath to show.^[3]

You can tell that corals require the sun’s rays to survive because the organisms die in polluted water.

Waste makes the water cloudy, which, in turn, blocks the coral’s access to sunlight, killing the zooxanthellae and their corals.^[4]

If white light in the wild promotes coral growth, white light in your reef tank at home will do the same.

Blue light is still the superior option. However, your corals can make do with white light.

Here is a list of shallow-water corals and their natural depth ranges. These are naturally exposed to white light in nature:

Montipora coral – 6 – 100 feet (2 – 30 meters)
Porites coral – 10 – 50 feet (3 – 15 meters)
Brain coral – 15 – 50 feet (5 – 15 meters)
Mushroom coral – 3 – 65 feet (1 – 20 meters)
Acropora coral – 16 – 82 feet (5 – 25 meters)
Staghorn coral – 15 to 60 feet (5 – 20 meters)

**Corals living in shallow water receive white light naturally in nature**

How Long Do Corals Need White Light?

Your corals require twelve hours of white light at the most. You can cut back to six hours if you want to maintain maximum intensity at all times.

But 8 to 12 hours is the traditional duration. You can follow this schedule:

9 am – 10 am	White light (20% intensity)
10 am – 11 am	White light (50% intensity)
11 am – 12 am	White light (75% intensity)
12 am – 8 pm	White light (100% intensity)
8 pm – 9 pm	White light (60% intensity)
9 pm – 11 pm	White light (20% intensity)
11 pm	Lights off

Your schedule may also look like this:

9 am: Lights On
8 pm: Lights Off

If you don’t have adjustable LEDs, you can switch the white lights on when you wake up and off when the sun goes down, so long as you keep the 8 – 12-hour rule in mind.

But you’re better off ramping the intensity up and down because sunlight ramps up and down.

Keep in mind that your reef tank has fish. You don’t want to stress them out by suddenly turning the lights on or off.

They require a gradual shift in light, not to mention a regular day/light cycle. Surprisingly, corals are no different.

You can’t expose them to 24 hours of white light. First of all, excess sunlight in the wild can cause bleaching by raising the water’s temperature.^[5]

Secondly, Oren Levy (Bar-Ilan University, Israel) performed a study that connected artificial lights at night to oxidative stress and lower photosynthetic performance in corals.^[6]

Blue and white lights had the most drastic impact on the coral’s physiology.

The marine biologist was trying to understand the consequences of artificial lighting from the coastlines on corals.

Apparently, the coast is growing brighter as human settlements expand. This is problematic because all living things require periods of darkness.

Artificial lighting from oil ships and trawlers has become a potential threat to corals off the coast of Israel.

Additionally, studies have found that artificial lighting negatively influences healthy population expansion in corals.^[7]

This is why aquarists switch to blue at night, as it makes the transition from day to night feel more natural.

Even though white lights offer better visibility, you shouldn’t switch them on at night. This will disturb both your fish and corals.

Here is a schedule that includes both blue and white lights for your corals:

9 am – 10 am	White light (20% intensity)
10 am – 11 am	White light (50% intensity)
11 am – 12 am	White light (75% intensity)
12 am – 6 pm	White light (100% intensity)
6 pm – 11 pm	Blue light
11 pm	Lights Off

**When lighting a reef tank with white light, it is best to include blue light as well**

What Is The Easiest Way To Apply White Light In A Coral Tank?

If you want to use white light in your reef tank, it is best to use a system programmed to change the lighting colors throughout the day.

The one that I recommend is the Hygger 24/7 Lighting Aquarium Light (link to Amazon). This system automates the previously mentioned cycle:

8 am to 6 pm: White color
6 pm to 10:50 pm: Blue color (imitates moonlight)
10:50 pm to 6 am: Lights off
6 am to 8 am: Orange color (imitates sunrise)
Repeat cycle.

Sticking to this schedule will allow you to enjoy the view of your corals under white light during the day, but also take advantage of the direct blue light.

It also benefits aquarium fish, which probably live alongside your corals.

Does White Light Make Corals Glow?

Reef tanks can look just as good under white light as they would under blue. However, don’t expect the corals to glow.

Many aquarists combine white with actinic blue to make the aquarium’s colors pop:

Will Using White Light For Corals Cause Algae?

Algae is only a mild concern. Yes, algae require light to grow. They use sunlight to photosynthesize.^[8]

Therefore, algae may become a nuisance in an aquatic environment with white LEDs, but only if your water has nutrients that support algae growth, such as nitrates and phosphates.

Pro Tip: Feeling uncertain about how to light your coral tank? Don’t worry, I’ve got you covered with my ultimate guide on the topic.

Conclusions

If you’re in a hurry, here’s a quick rundown of the key points mentioned above:

White light can be beneficial for corals, as it contains all wavelengths of the visible spectrum, including blue and red, which are important for coral growth.
Some coral species are naturally exposed to white light in the wild and can thrive in it. This mainly includes corals living in shallow water.
Blue light is still considered the superior option for coral tanks, but white light can be used as an alternative.
Corals need a maximum of 12 hours of white light per day, with a traditional duration of 8 to 12 hours.
The intensity of the white light should be adjusted throughout the day to mimic natural sunlight, with higher intensity in the middle of the day and lower intensity in the morning and evening.