5. Lighting

Below is a history and information about various forms and kinds of lights. Today though, basic LEDs with a mix of colors and programming features dominate the industry.

Aquarium Lighting                                                                       Scroll down for LEDs
Fluorescent (T5)Lighting is one of the more important factors for the aquarium.  Our focus is saltwater aquariums and more specifically a basic mixed reef tank. The animals usually include what are generally considered “easy-to-keep” corals, fish, and invertebrates (shrimp, crabs, anemones, snails, etc.).Many organisms such as plants, algae, corals, and some bacteria synthesize food directly from carbon dioxide using enery from light – photosynthesis.  It is thought that fish depend on light, much like humans, for immune function and general health. Lastly, reef keepers enjoy the bright look and varied colors and shapes in their tanks illuminated by the right lighting.


Since most of the animals kept in the hobby live in and are collected from shallow, atoll coral reefs on and near the equator, we start by analysing the quantity and quality of natural sunlight found there.

Basic physics teaches us that light has a wave-particle duality. Wave properties measured in wavelength and frequency (spectrum, color), and particle properties (photons, intensity).

Quality of light – spectrum, color, appearance, Kelvin (K), CRI, CCT
Visible light (Visible Spectrum) is a narrow band of the electromagnetic spectrum that falls in the 380nm to 770nm range that can be perceived by the human eye.  The slightly narrower subset used in photosynthesis from 400nm-700nm is called Photosynthetic Active Radiation (PAR).

There are two systems of measurement commonly used to describe the color properties of a light source: “color temperature” (K for Kelvin rating) which expresses the color appearance of the light itself, and “color rendering index” (CRI), which suggests how an object illuminated by that light will appear in relation to its appearance under other common light sources. Sunlight is said to have a CRI of 100.

Quantity of light – intensity, flux, lux, lumens, PAR, PPFD

Lux (lumens/sq meter) in tropical reefs has been measured to be between 110,000 and 120,000 Lux at the surface of the reef and 20,000-25,000 Lux one meter below the surface. PAR studies using quantum light sensors (aka PAR meters) have measured light intensities on a clear day, over a tropical coral reef, just below the water surface, ranging from 500 PAR early morning to approximately 2000 PAR mid-day when the sun is directly overhead. The term, PAR (photosynthetically active radiation), refers to the amount of light that falls in the band used for photosynthesis.

Photosynthetic light below the water surface
Photosynthesis works in the same biochemical ways for both terrestrial plants and aquatic corals, but corals “see” a different quality and quantity of light because water filters and reflects light. Saltwater absorbs even more light than freshwater. The higher energy blue side of the spectrum penetrates to greater depths. In an aquarium with 2 feet of clear water, most of wavelengths will make it to the corals.

Photosynthetically Usable Radiation (PUR)
Of the narrow PAR band of light, are there narrower bands that are more useful for photosynthesis in general, and for corals more specifically?  Here is where one of many debates begins and doesn’t seem to end. The answer seems to be, NO, as shown by the chart below. This coral uses light energy across the spectrum.

There is some evidence though, and a belief (a quite strong belief for some) that there are two spectrum “spikes” most or more important for coral growth and color.  One broad spike in the purple/blue 400 to 500 nm range and a narrower red spike around 660/670.  Lastly, some adhere almost dogmatically to the belief that the blue range is the most important spike, in part because the blue spectrum light best penetrates water, and a belief they are keeping “deep water” corals – those that live in and are collected from depths, 15 to 60 feet.

“This experiment’s results suggest information potentially valuable for hobbyists – that rates of photosynthesis were essentially the same under these two distinctly different light sources. Other than aesthetic value, there appears to be no advantage, photosynthetically speaking, in using high Kelvin lamps.” Dana Riddle, Advanced Aquarist Magazine, Feb 2002

Now, let’s turn to our typical mixed reef system and the available light sources in the hobby. Artificial lighting companies and hobbyists try to mimic mother nature and even try to do her one better.

In general, we are looking for at least 100 PAR (or 3000 lux) intensity on the sand bed (bottom of the tank) and the required color spectrum for the animals.  Stagger corals by placing them on your live rock aquascape at depths (low/sand bed, mid tank, and high) according to their needs. Higher in the tank for more light intensity. Of course, the height above the water surface of the lighting system will influence PAR values and coverage.

Most clams, most SPS corals, and carpet anemones for example require high light intensity.

The various wavelengths within a given light source—its “color makeup”— can vary greatly and it will still appear white.

A 250W MH covers a tank surface area of 36″X30″.
A 36″ T5 (6tube x 39watt) fixture covers an area of 36″x24″
A 24″ LED fixture with 90 bulbs covers an area of  24″x18″

Many reefkeepers employ a 12-hour photoperiod. With multi-light systems, you can use timers to vary the intensity by varying the number of lights on at any one time. Usually, one bulb comes on for an hour, then all bulbs for 10 hours, then one light is left on for an additional hour while the others are turned off. This is one method to duplicate the sun passing over the reef.

Fixtures are made-up of bulbs, reflectors, and electronics. Lighting fixtures can be built into canopies, hung from the ceiling or light stands, or placed directly on the tank walls with fixture stand attachments. Combo systems have mixes of bulb type, intensities, and colors in the same fixture.

Consider PAR per watt, PAR per dollar, operating costs, coral growth rates, and your personal preference for the appearance of your tank under a certain lighting scheme.  Also consider usable PAR, PUR, PPFD, and CRI.

The color temperature of light is the ratio of red to blue light waves measured in degrees Kelvin (K). At 6000 degrees (K), the ratio between red and blue is equal. The higher the content of blue light waves, the higher the color temperature. Blue light penetrates saltwater best and corals most benefit from 400-420 nm (more violet and near UV) and 440-470 nm wavelengths of blues (blue at 470, and royal blue at 450.

Coral Health and Color:
In nature, many corals have made adaptations to the the effects of harmful UV-A and UV-B rays. Corals have developed protective pigments that are often blue, purple, or pink in color. Most corals that contain these pigments come from shallow waters where the amount of UV-A and UV-B light is higher than in deeper areas of the reef.  Corals can lose their color due to the low light levels and blocked UV in an aquarium — doesn’t mean they are unhealthy.

Corals may grow more brown under low light intensity and lighten under higher light levels.

Corals may show more colors with exposure to blue spectrum lighting.  Some corals are collected from depths of 15 to 65 feet where mostly all but blue wavelengths have been filtered out.  Why not all blue then for our tanks?  Many just don’t like the look, so a popular combination is part bright daylight wide spectrum white and part blues (aka actinic).

General System Comparison

LED (light emitting diodes)

LED Directory – System Manufacturers, Retailers, Resellers and DIY
(We will try to identify the OEMs. A basic, then more detailed comparsion matrix is in the works.  Please check back.)

 ManufacturerBrand/ModelWeb siteNotes                 
 AcanLighting http://www.acanlighting.com/                  
 Apollo Reef LED http://www.apolloreefled.com                  
 Aqua Medic http://www.aqua-medic.com                  
 AquaIllumination (AI) http://www.aquaillumination.com                  
 AquaRAY http://www.aquarayusa.com                  
 AquaStyle http://www.aquastyleonline.comDIY                 
 AquaticLife http://www.aquaticlife.com/                  
 Aquatronica http://www.aquatronica.comItaly                 
 Aqueon http://www.aqueonproducts.com                  
 Arcadia http://www.arcadia-aquatic.comUK                 
 BlueLine http://www.bluelineaquatics.com                  
 BlueMoon Aquatics http://www.bluemoonaquatics.com                  
 BoostLED http://www.boostled.com                  
 BuildMyLED http://www.buildmyled.com                  
 BulkReefSupply http://www.bulkreefsupply.com/Retailer                 
 Bysen http://www.bsled.com/China                 
 Cidly http://www.cidly.comChina                 
 CoralVue http://www.coralvue.com/US Wholesaler                 
 Current USA http://www.current-usa.com                  
 Eco Lamps http://www.eco-lamps.com/reef.htm                  
 Ecoray http://www.ecorayled.com                  
 EcoTech Marine http://www.ecotechmarine.com/                  
 Ecoxotic http://www.ecoxotic.com                  
 ELOS http://www.elos.euItaly                 
 EverGrow http://www.evergrowlighting.comChina                 
 GHL http://ghlna.com/                  
 Giesemann http://www.giesemann.de/Germany                 
 Illumagic Opto http://www.illumagic.com.tw                  
 Illuminarium http://illuminarium-inc.com                  
 Innovative Marine http://www.innovative-marine.com/                  
 JBJ http://www.jbjlighting.com                  
 Kessil http://www.kessil.com                  
 LED Group Buy http://www.ledgroupbuy.com                  
 LED Pacific http://www.ledpacific.com                  
 MakersLED http://www.makersled.comDIY                 
 Mame Design http://www.mame-design.jpJapan                 
 MarineDepot http://www.marinedepot.com/Retailer                 
 Marineland http://www.marineland.com/                  
 MarineReefLED (MRL) http://www.marinereefled.co.uk/                  
 Maxspect http://www.maxspectusa.com/                  
 Meerwasser TechnikAquaConnecthttp://www.meerwassertechnik.com/                  
 MVAVA http://www.mvava.com                  
 Nano Box http://nanoboxreef.com/                  
 Orphek http://www.orphek.com                  
 Pacific Sun http://www.pacificsunusa.com                  
 Rapid LED http://www.rapidled.com/DIY, fixtures                 
 Reef H2O http://www.reefh2o.comWholesaler                 
 Reef LED Lights http://www.reefledlights.comDIY                 
 ReefBrite http://www.reefbrite.com                  
 Shenzhen BaishengBysenhttp://www.bysenled.com                  
 Shenzhen SanxinbaoEverGrowhttp://www.evergrowlighting.com                  
 Steves LEDs http://www.stevesleds.comDIY                 
 SunBrite Lighting http://www.sunbritelighting.com                  
 Tropical Marine Centre http://www.tropicalmarinecentre.co.ukUK Wholesaler                 
 Tunze http://www.tunze.com                  
 VASCA http://www.vascaaquariumsupply.com/Wholesaler                 
 Vertex http://www.vertexaquaristik.com                  
 Volx Japan http://www.volxjapan.co.jpJapan                 
 WavePoint http://www.wave-point.com                  
 ZET Light http://www.zetlightusa.com/







Orbitec (note, patent issues)

PFO (Solaris, Galileo models)





Shenzhen Jiangjing Lighting Co., Ltd.  (OEM)

Superstar LED Lighting Limited




LED bulbs and chips
Eco-Lamps, Epistar, CREE, Osram, Philips Luxeon, SemiLEDs, BridgeLux

Bulbs and chips from Taiwan:
The Taiwan government-sponsored Industrial Technology Research Institute (ITRI) has joined with the 14 makers of LEDs and LED chips. The companies are: Epistar, Formosa Epitaxy, Arima Optoelectronics, Opto Tech, Tyntek, Ledtech Electronics, Unity Opto Technology, Para Light Electronics, Everlight Electronics, Bright LED Electronics, Kingbright, Lingsen Precision Industries, Ligitek Electronics and Lite-On Technology.

Spectrum and color

Note that blue and royal blue are significantly different.

3500K is only slightly bluer than halogen and feels like you’re next to a cozy fireplace.
6500K feels like you’re under a cloudless arctic sky.


Optics affect coverage and spot-lighting.  Some fixtures have interchangeable lenses.

Narrow optics can produce high PAR but also spot-lighting, shadows, color variation, and even the chance of burned corals.
Also, coverage/spread can be poor with high PAR directly under the lights, but unacceptably low PAR on the fringes of the light pattern.

Common LED OEM models.

PAR Measurements

AquaIlluminations LED (AI70watt) test, recently reported by a hobbyist, 2 fixtures with slightly overlapping light

6″ – 1650
12″ – 1370 (water surface)
16″ – 915 (4″ water depth)
19″ – 690 (7″ water depth)
24″ – 560 (12″ water depth)

ReefKoi says, “When we did real world PAR testing over a reef aquarium we mounted the lights ~5? above water and got 965 at the surface, 500+ 5? down and 200+ 19? deep and 115 at the bottom 23? down…….I think its respectable, considering the wattage used? I mean a 150 HQI would be lucky to get 20 PAR at 23? deep I’m guessing.”

ReefLEDLights says, “A 250 watt 10K XM light produces about the same PAR as a 400 watt Radium. This is why I claim such a range. The hard numbers are 48 XR-E LEDs on a 8?x24? heatsink using 80 degree optics will produce 296 PAR at 24?, when driven at 700mA. When driven at 800mA the same fixture will produce 323 PAR. A 400 watt Radium produced 310 PAR at that distance and the 250 watt 10K XM produced 305 PAR.”

Sanjay Joshi says, “Based my experience with light measurements and 20+ years of keeping corals I have found that light levels of 100 PAR, at the bottom of tank is usually more than enough to allow keeping a wide range of corals successfully. Incidentally, my personal 500G (84″LX48″WX30″H) tank lit by 3 400W Ushio 14000K lamps in a Lumenarc reflector mounted about 12″ from the water surface has PAR readings at the bottom ranging from 80-120. With PAR levels averaging 100 at the bottom of the tank, there is enough of a light gradient to allow keeping high light loving corals in the top ½ to 2/3rd of the tank, with lower light corals scattered in the lower half. Most acropora and other light loving corals will thrive at light levels of 300-400.”

Coverage or spread (refer to manufacture charts)
A 250W MH covers an area of 36″X30″.
A 36″ T5 (6tube x 39watt) fixture covers an area of 36″x24″
A 24″ LED fixture with 90 1-watt bulbs covers an area of  24″x18″

Spectrum and Color
1 Royal Blue to 1 Cool White will give you a 10-12K look.
2 Royal Blue to 1 Cool White will give you a 18-20K look.
Blue and royal blue LEDs are significantly different from each other.

CREE manufactures a range of different LEDs, and the term “binning” refers to the method that the company uses to sort all these LEDs in terms of their dominant wavelength (color) and luminous flux (brightness). The resultant “bin number” is then used by manufacturers of LED products to specify the color and brightness of the LEDs they wish to use.

Metal Halide (MH)

An older, mature technology already covered by many sources.

Fluorescent (T5)

Click here …

Plasma Arc

Plasma Arc Lighting

StrayLight Optical SeaShine

Natural Sunlight

In our KIS system, NOTHING comes close to natural sunlight.  Like flowers opening up, the coral polyp extension and detail that can be easily seen by the naked eye is far greater than any artificial light source.

More indepth treatment of lighting here.