Why Is Lighting Important?
In natural reef environments, sunlight penetrates the ocean and provides energy for photosynthetic organisms.
Many corals contain microscopic algae called zooxanthellae that live within their tissue. These algae use light to produce energy through photosynthesis, which is then shared with the coral.
Proper lighting helps:
- Support coral growth
- Enhance coral colouration
- Promote healthy biological processes
- Improve fish and coral viewing
- Replicate natural reef conditions
- Establish day and night cycles
Without adequate lighting, photosynthetic corals will struggle to survive.
Fish-Only vs Reef Aquarium Lighting
Fish-Only Marine Aquariums
If your aquarium contains only fish and live rock, lighting requirements are relatively simple.
The primary goals are:
- Viewing enjoyment
- Natural day/night cycles
- Enhanced fish colouration
Most quality LED marine lights are more than sufficient for fish-only systems.
Reef Aquariums
Corals require lighting that delivers the correct intensity and spectrum for photosynthesis.
The requirements vary depending on the type of coral being kept.
Understanding PAR
PAR stands for:
Photosynthetically Active Radiation
PAR measures the amount of usable light available for photosynthesis.
Unlike wattage, PAR tells us how much light corals actually receive.
Typical PAR Requirements
|
Coral Type |
Recommended PAR |
|---|---|
|
Soft Corals |
50–150 |
|
LPS Corals |
75–200 |
|
Mixed Reef |
100–250 |
|
SPS Corals |
200–500+ |
PAR levels should be measured where the coral is placed, not at the water surface.
Understanding Spectrum
Light spectrum is equally important as intensity.
Marine LEDs are designed to replicate the wavelengths that penetrate ocean water most effectively.
Key Reef Lighting Colours
Royal Blue
One of the most important wavelengths for coral growth.
Benefits:
- Supports photosynthesis
- Enhances fluorescence
- Encourages coral colouration
Blue
Provides additional photosynthetic support while producing the classic reef appearance.
Violet and UV
Modern reef fixtures often include violet and UV channels.
Benefits:
- Increased fluorescence
- Enhanced coral pigmentation
- Improved colour development
White
Adds visual brightness and improves natural viewing.
Excessive white light may encourage nuisance algae if nutrients are elevated.
Red and Green
Used sparingly in modern reef lighting systems.
They can improve colour rendition but are typically a small part of the overall spectrum.
Types of Marine Aquarium Lighting
LED Lighting
LED lighting has become the dominant choice for marine aquariums.
Benefits
✔ Energy efficient
✔ Low heat output
✔ Fully controllable
✔ Long lifespan
✔ Customisable spectrum
✔ Sunrise and sunset simulation
Popular brands include:
- Ecotech Marine Radion
- AI Hydra
- AI Blade
- Red Sea ReefLED
- Kessil
- Reef Factory
- Maxspect
LEDs are now the preferred solution for most marine aquariums.
T5 Fluorescent Lighting
T5 lighting was once the gold standard for reef aquariums.
Benefits
✔ Excellent spread
✔ Uniform coverage
✔ Proven coral growth
Drawbacks
- Higher power consumption
- Regular bulb replacement
- Increased heat production
Many successful reef aquariums still use T5 systems or hybrid LED/T5 setups.
Hybrid Lighting
Hybrid systems combine LED and T5 technology.
Benefits
✔ Excellent coverage
✔ Strong PAR levels
✔ Reduced shadowing
✔ Exceptional coral growth
Hybrid systems remain popular among advanced SPS reef keepers.
Choosing Lighting Based on Coral Type
Soft Coral Aquariums
Examples:
- Zoanthids
- Mushrooms
- Leather corals
Requirements:
- Moderate lighting
- PAR 50–150
Most entry-level reef LEDs can support soft corals successfully.
LPS Coral Aquariums
Examples:
- Euphyllia
- Acans
- Blastomussa
- Favia
Requirements:
- Moderate to high lighting
- PAR 75–200
Many LPS corals prefer stable lighting rather than extreme intensity.
SPS Coral Aquariums
Examples:
- Acropora
- Montipora
- Stylophora
Requirements:
- High PAR
- Strong blue spectrum
- Excellent consistency
SPS corals are typically the most demanding in terms of lighting performance.
Understanding Photoperiod
Photoperiod refers to how long your lights remain on each day.
A typical reef lighting schedule:
Example
|
Time |
Lighting |
|---|---|
|
08:00 |
Sunrise begins |
|
10:00 |
Full intensity |
|
18:00 |
Begin ramp down |
|
20:00 |
Blue-only viewing |
|
21:00 |
Lights off |
Total photoperiod:
8–12 hours
Running lights for excessively long periods can increase algae growth without providing additional coral benefits.
What Is Coral Acclimation?
When introducing new corals or upgrading lighting, sudden increases in intensity can stress or bleach corals.
Most modern lighting systems include acclimation modes that gradually increase output over several weeks.
Benefits include:
✔ Reduced stress
✔ Lower bleaching risk
✔ Improved coral adaptation
Always acclimate new corals to stronger lighting.
Common Marine Lighting Mistakes
Choosing Lights Based on Wattage
PAR and coverage are far more important than wattage alone.
Insufficient Coverage
A powerful light with poor spread may leave shaded areas in the aquarium.
Always consider:
- Aquarium length
- Aquarium width
- Coral placement
Excessive Intensity
More light is not always better.
Signs of excessive lighting:
- Coral bleaching
- Reduced polyp extension
- Tissue recession
Ignoring Mounting Height
Mounting height significantly affects:
- PAR distribution
- Light spread
- Shadowing
Follow manufacturer recommendations where possible.
Signs Your Corals Are Receiving Good Light
Healthy corals typically display:
✔ Strong colouration
✔ Good polyp extension
✔ Consistent growth
✔ Stable tissue health
✔ Improved fluorescence
Monitoring coral behaviour is often more useful than chasing specific numbers.
Lighting and Algae Growth
Lighting often gets blamed for algae outbreaks, but nutrients are usually the primary cause.
Excessive nitrate and phosphate combined with long photoperiods can encourage algae growth.
The solution is usually:
- Improved nutrient control
- Appropriate photoperiod
- Regular maintenance
Not simply reducing light intensity.
How Many Lights Do You Need?
This depends on:
- Aquarium dimensions
- Coral type
- Mounting height
- Fixture design
As a general rule:
Small Aquariums
One fixture may be sufficient.
Medium Aquariums
Two fixtures often provide better coverage.
Large Reef Aquariums
Multiple fixtures or hybrid systems usually deliver the most even illumination.
Final Thoughts
Lighting is one of the most influential factors in reef aquarium success. By understanding PAR, spectrum, coverage, and photoperiod, you can create the ideal environment for your fish and corals while enhancing the appearance of your aquarium.
Modern LED lighting systems offer exceptional control and performance, making it easier than ever to replicate natural reef conditions and achieve healthy coral growth.
The key is choosing a lighting solution that matches your aquarium size, livestock, and long-term reef-keeping goals.
Need Help Choosing the Right Marine Aquarium Lighting?
At Charterhouse Aquatics, we stock a wide range of marine lighting solutions from leading brands including Ecotech Marine, AI, Red Sea, Kessil, Reef Factory and Maxspect. Our marine specialists can help you choose the ideal lighting system for your aquarium, whether you’re setting up a fish-only marine tank, mixed reef, or SPS-dominated reef system.
