Full Spectrum or Blue? How Lighting Impacts Coral Growth and Your Aquarium's Appearance
Lighting plays a bigger role in a reef tank than just helping you see what's inside. It affects coral growth, coloration, and even how your tank feels in your living space. No matter if you're in the early planning stages of a new build or have an established reef tank, the choice between full spectrum and heavy blue lighting can make a big difference.
Let’s look at both options so you can make the best choice for your tank.
Understanding Full Spectrum and Blue Lighting
Full spectrum lighting is designed to mimic natural daylight. It includes a wide range of wavelengths, giving your tank a look that’s closer to what you’d see if you went snorkeling in shallow ocean water.
Blue spectrum lighting focuses mainly on the blue and violet range. This is what makes coral colors pop, especially those fluoresent greens, oranges, purples and reds.
Each lighting type serves a purpose, and they both come with their own strengths.
Corals Fluorescing Under Heavier Blue Lighting
Corals Under Natural-Looking Full Spectrum LightingQuick Comparison
| Feature | Full Spectrum | Blue Spectrum |
|---|---|---|
| Appearance | Natural daylight | Neon, glowing effect |
| Room Lighting | Comfortable, not overpowering | Can cast strong blue hue |
| Best For | Shallow water corals, mixed reefs | Deep water corals, frag tanks, photography |
| Color Pop | Subtle, more realistic | More intense fluorescence |
| Ideal Use | Shared spaces and display | Highlighting coral colors |
Why Choose Full Spectrum?
There are a few solid reasons aquarists lean toward full spectrum lighting:
- More Natural Look: It gives the tank a daylight appearance that feels more like the ocean and less like a black light night at the bowling alley.
- Comfortable for Room Lighting: If your tank is in your living room or shared space, full spectrum light feels more balanced. It doesn’t cast that deep blue glow all over your walls and ceiling. Additionally, your neighbors won't be wondering what the heck is glowing in your house when the sun goes down.
- Consistent Coral Growth: Historically, people believed full spectrum lighting helped promote better overall coral growth. That’s especially true for shallow water corals, which naturally receive a broader range of light in the wild.
When Blue Spectrum Lighting Shines
Blue lighting isn't just about looks. It plays a big part in how certain corals grow and display their colors. Here's why it might be the right choice for your setup:
- Unbeatable Fluorescence: This is usually the number one reason reefers choose heavy blue lighting. Under deep blue and violet light, corals can glow with intense colors that you just can't get from a full spectrum setup.
- Perfect for Photos and Videos: If you're into photographing or filming your tank, blue light combined with an orange filter brings out those neon colors that look amazing on screen.
- Low PAR Needs with High Impact: Many of these deep-water species don’t require high PAR levels. What they do need is the right spectrum. Blue and UV light hit the sweet spot for their energy needs and help bring out their full potential in color and health.
- Highlight Hidden Colors: Some colors are only visible under blue lighting. Corals that might look plain during the day can show surprising patterns and highlights at night under blue light.
Mixing It Up: The Best of Both Worlds
Most modern reef lights allow you to customize your spectrum. That means you don’t have to choose just one.
Here’s how some hobbyists use both:
- Daytime Settings
Run full spectrum during the day to enjoy a natural look and support coral growth.
- Evening Pop
Switch to a bluer setting in the evening to enjoy the fluorescence and give your corals a showcase moment.
- Photography Settings
Use a blue-heavy spectrum with a filter when you want to take photos or video that really highlight your corals' colors. Some LED light fixtures even have "Photo Mode" lighting presets.
Tip: If you don't have an orange camera filter, taking photos or video under full spectrum lighting usually produces better results with most phone cameras.
Personal Preferences and Practical Tips
Everyone has their own take, and that's totally okay. Some people want their tank to feel like a slice of the reef. Others want it to look like a laser show. Here are a few things to keep in mind:
- Think About Where Your Tank Lives
If it's in a living space, full spectrum might be more comfortable on your eyes in the long run.
- Know Your Corals
Some species respond better to specific wavelengths. Do a little research to understand what your corals prefer.
- Think About the Fish
Most fish look their best under full spectrum lighting. Under blue lighting, their colors are typically more muted, putting the spotlight on the corals instead.
More Frequently Asked Questions About Reef Tank Lighting
Can I run both full spectrum and blue lighting in the same tank?
Absolutely. Many modern reef lights allow you to customize the spectrum throughout the day. It’s common to run full spectrum during daylight hours and shift to a bluer spectrum in the evening for visual effect. In some cases, it's also common to mix different LED light fixtures together over the same tank. For example, you may choose to run both the AquaIllumination Coral Grow (closer to full spectrum) and Coral Glow (heavier in the blue spectrum) LED strips to get the best of both worlds.
How long should I keep my lights on each day?
Most reef tanks thrive with 8 to 12 hours of light per day. Some hobbyists also include a short ramp-up and ramp-down period to mimic natural sunrise and sunset. Not necessary for success, but it's a cool visual effect watching your tank gradually "wake up" in the morning.
What is the Best Reef Tank Lighting Schedule??
If you're just getting started, we recommend following the 1-8-1 ratio. 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.
Learn More: What is the Best Reef Tank Lighting Schedule?
Is PAR the same as spectrum?
No, PAR (Photosynthetically Active Radiation) measures light intensity, while spectrum refers to the specific wavelengths of light being emitted. Both are important to get right for coral health.
Do I need a PAR meter to set up my lighting?
It’s not always required, but we highly recommend using one. Too much light can quickly lead to coral bleaching, and too little light often causes a slow decline that's easy to overlook. Buying or borrowing a PAR meter helps you dial in the right intensity and avoid both extremes. It’s a small step that can save your corals and your wallet in the long run.
Learn More: Keep Coral HAPPY & Dial in Your Reef Tank Lights With a PAR Meter!
Can LED lights grow all types of coral?
Yes, if you pick the right ones. LED lighting has come a long way and is capable of supporting everything from softies to SPS corals, as long as intensity and spectrum are dialed in correctly.
Learn More: Get Lighting Right the First Time
Can I Use a Planted Aquarium Light for My Reef Tank?
No. Even high-end freshwater aquarium lights aren't suitable for reef tanks because they simply don't deliver the right spectrum to support coral health. Freshwater fixtures are usually rich in green, yellow, and red wavelengths, which give off a white appearance, but they fall short in the blue range around 400 to 450 nanometers that corals rely on for health and growth.
Adam has been reef keeping since 2010 and got his start on the Bulk Reef Supply Customer Service team. He believes the best tanks are built around what you enjoy, not what’s trending. Adam is especially interested in simplifying the hobby, exploring the latest gear, and helping others focus on long-term success over chasing perfection.
Login and Registration Form