Lighting is one of the most critical components of any successful reef aquarium. While marine fish can thrive under relatively simple lighting, corals rely on high-quality illumination to grow, maintain vibrant colours, and support the tiny symbiotic algae that provide much of their energy.
Choosing the right reef lighting can seem overwhelming. With so many brands, mounting options, spectrum settings, PAR values, and control features available, it’s easy to wonder where to start. The good news is that understanding a few key principles will help you select lighting that suits both your aquarium and the corals you want to keep.
In this comprehensive guide, we’ll explain how reef lighting works, why it matters, the different types of aquarium lights available, and how to create the perfect lighting schedule for a healthy, colourful reef aquarium.
Why Is Reef Aquarium Lighting So Important?
Unlike fish, most corals depend on light as their primary energy source.
Tiny algae called zooxanthellae live inside coral tissue. Through photosynthesis, these algae convert light energy into nutrients that the coral uses for growth and survival.
Without appropriate lighting:
- Coral growth slows
- Colours fade
- Tissue begins to deteriorate
- Photosynthesis decreases
- Corals may eventually die
Good lighting is one of the foundations of successful reef keeping.
Understanding Photosynthesis
Zooxanthellae require specific wavelengths of light to photosynthesise efficiently.
The most important wavelengths fall within the blue and violet portions of the spectrum.
These wavelengths penetrate seawater more effectively than red or yellow light, which is why natural coral reefs appear predominantly blue beneath the surface.
Modern reef lights are designed to maximise these useful wavelengths.
What Is PAR?
One of the most commonly discussed terms in reef lighting is PAR.
PAR stands for:
Photosynthetically Active Radiation
Rather than measuring brightness, PAR measures the amount of usable light available for photosynthesis.
Higher PAR values generally mean more energy is available for corals.
Typical PAR Requirements
Different corals require different light intensities.
Soft Corals
Examples include:
- Mushroom Corals
- Leather Corals
- Zoanthids
Recommended PAR:
50–150
LPS Corals
Examples include:
- Hammer Corals
- Torch Corals
- Frogspawn
- Acans
Recommended PAR:
75–200
SPS Corals
Examples include:
- Acropora
- Montipora
- Stylophora
Recommended PAR:
200–400+
Higher light isn’t always better—stability and consistency are equally important.
Understanding Spectrum
The colour of your reef light is determined by its spectrum.
Modern LED reef lights usually combine several colours including:
- Royal Blue
- Blue
- Violet
- UV
- White
- Cyan
- Red
- Green
Each wavelength performs a different role.
Blue Light
Blue light:
- Drives photosynthesis
- Enhances coral fluorescence
- Improves coral colour
Most reef aquariums spend much of the day under predominantly blue lighting.
White Light
White LEDs improve the natural appearance of the aquarium and make fish colours look more realistic.
Too much white light can encourage nuisance algae if nutrient levels are high.
Violet and UV
These wavelengths help:
- Stimulate fluorescence
- Improve coral pigmentation
- Support photosynthesis
Most premium reef lights include multiple violet channels.
Red and Green
Used sparingly to improve colour rendition.
Too much red light may encourage algae growth.
Types of Reef Aquarium Lighting
Several lighting technologies are available.
LED Lighting
LEDs have become the industry standard.
Advantages include:
- Low power consumption
- Adjustable spectrum
- Minimal heat
- Long lifespan
- App control
- Sunrise and sunset simulation
Most modern reef aquariums now use LED lighting.
T5 Fluorescent Lighting
T5 lighting was once the gold standard for SPS reefs.
Benefits include:
- Excellent light spread
- Even PAR distribution
- Proven coral growth
However:
- Bulbs require regular replacement.
- Power consumption is higher.
- Less customisable than LEDs.
Many advanced reef keepers still combine T5 lighting with LEDs.
Metal Halide Lighting
Metal halides produce exceptional PAR and natural shimmer.
Benefits include:
- Outstanding coral growth
- Deep light penetration
- Natural appearance
Disadvantages include:
- High electricity consumption
- Significant heat production
- Annual bulb replacement
Although less common today, some dedicated SPS enthusiasts continue to use metal halides.
Choosing the Right LED
Several excellent reef lighting manufacturers are available.
Popular brands include:
- Ecotech Marine Radion
- AI Hydra
- AI Prime
- Red Sea ReefLED
- Kessil
- Aqua Illumination Blade
- Maxspect
- Reef Factory
- Philips CoralCare
- Orphek
Each offers different mounting options, power levels, and control features.
How Many Lights Do You Need?
This depends on:
- Aquarium length
- Aquarium width
- Coral type
- Aquascape
As a rough guide:
Nano Aquariums
Often require:
- One LED fixture
Medium Aquariums
Usually require:
- Two LED fixtures
Large Reef Aquariums
May need:
- Three or more fixtures
Uniform light coverage is generally more important than simply increasing intensity.
Mounting Your Lighting
Common mounting options include:
Tank Mount Arms
Simple to install and popular for rimless aquariums.
Hanging Kits
Provide maximum flexibility and excellent light spread.
Canopy Installation
Ideal for custom-built aquariums.
Whichever method you choose, ensure adequate ventilation around the lights.
Photoperiod
Most reef aquariums receive between:
8–12 hours of light daily.
A typical schedule might be:
- Sunrise: 8:00 am
- Full daylight: 10:00 am–6:00 pm
- Sunset: 6:00 pm–8:00 pm
- Moonlight: Optional
Gradual transitions reduce stress for both fish and corals.
Should You Use Moonlights?
Many LED systems include low-intensity moonlight modes.
These:
- Create attractive evening viewing
- Simulate lunar cycles
- Minimise sudden darkness
However, moonlights should remain very dim and are generally best used for only a short period after the main lights switch off.
Acclimating Corals to New Lights
One of the biggest mistakes is installing powerful new lighting at full intensity.
This may cause:
- Coral bleaching
- Tissue recession
- Stress
Instead:
- Start at 30–50% intensity.
- Increase gradually over several weeks.
- Use the built-in acclimation mode if available.
Most premium LED systems include automated acclimation programmes.
What Is Coral Bleaching?
Bleaching occurs when corals expel their zooxanthellae due to stress.
Possible causes include:
- Excessive light
- Rapid lighting changes
- High temperatures
- Poor water chemistry
A bleached coral appears pale or white because its algae have been lost.
Lighting should always be adjusted gradually.
Lighting and Algae
Lighting alone rarely causes algae.
Algae outbreaks usually result from a combination of:
- Excess nutrients
- High phosphate
- High nitrate
- Poor maintenance
- Long photoperiods
Reducing lighting intensity without addressing nutrients often fails to solve the problem.
Shimmer Effect
One feature many reef keepers enjoy is the natural shimmer created by moving water.
Lights that produce excellent shimmer include:
- Kessil
- Radion
- AI Hydra
Shimmer closely resembles sunlight passing through ocean waves.
Diffusers
Some LED systems offer optional diffusers.
Benefits include:
- Softer shadows
- Improved colour blending
- More even PAR
The trade-off is a small reduction in maximum light output.
Smart Lighting Control
Many modern reef lights can be controlled via smartphone apps.
Features often include:
- Intensity adjustment
- Spectrum control
- Sunrise simulation
- Sunset simulation
- Cloud effects
- Lunar cycles
- Acclimation mode
Programming your lights helps create consistent conditions for coral growth.
Should You Measure PAR?
If possible, yes.
PAR meters help determine:
- Light intensity
- Shadowed areas
- Coral placement
- Fixture positioning
Many local aquarium stores and clubs offer PAR meter rental services.
Measuring PAR removes much of the guesswork from reef lighting.
Common Lighting Mistakes
Too Much Light
Higher intensity isn’t always better.
Corals can bleach under excessive PAR.
Too Little Light
Insufficient lighting slows growth and reduces colouration.
Constantly Changing Settings
Frequent spectrum or intensity changes stress corals.
Find a stable programme and leave it largely unchanged.
Ignoring Coral Placement
Place corals according to their lighting requirements.
High-light SPS should be positioned higher in the aquascape, while lower-light soft corals and many LPS corals often perform better lower down or in partially shaded areas.
Which Lighting Is Best?
For most reef keepers today, a quality LED system offers the best combination of:
- Performance
- Energy efficiency
- Flexibility
- Reliability
- Long lifespan
Premium LED fixtures provide outstanding coral growth while offering complete control over spectrum and intensity.
Final Thoughts
Lighting is one of the most important investments you’ll make when building a reef aquarium. By understanding PAR, spectrum, coral requirements, and photoperiod, you can create the stable conditions needed for healthy coral growth, vibrant colours, and long-term reef success.
Whether you’re keeping soft corals in a nano aquarium or growing demanding SPS colonies in a large reef system, choosing the right lighting—and using it consistently—will have a significant impact on your aquarium’s health and appearance. Combine quality lighting with stable water chemistry, good water flow, and proper nutrition, and your reef will have everything it needs to thrive.
At Charterhouse Aquatics, we stock an extensive range of premium reef lighting systems, mounting arms, hanging kits, LED accessories, and PAR meters from leading brands including Ecotech Marine, Aqua Illumination, Kessil, Red Sea, Maxspect, Reef Factory, Orphek, and more. Our experienced team is always available to help you choose the perfect lighting solution for your reef aquarium.
