You have probably come across the term correlated color temperature when reading about LED aquarium lighting. Being familiar with the concept is an important factor if you want to maximize the growth of the inhabitants of your aquarium.
The Concept Explained
Correlated color temperature is measured in Kelvin and represents the temperature needed for a theoretical standardized material (black body radiator) to emit light of comparable hue to that of the light source.
When metal is heated, the color of the light emitted will gradually change in appearance, from red to orange, yellow, white, blue-white and then to deeper colors of blue.
Lower color temperatures (2700 – 3000 K) produce warm colors (yellow-red) while color temperatures over 5000 K produce cool colors (blueish white). In comparison, regular incandescent household light bulbs usually come with temperatures of 2700 K and daylight lies around 5500 – 6500 K.
The Importance Of Wavelength
The characteristics of light emitted will change according to the stated temperatures of the light source. A higher color temperature will produce a more blueish light which will have a shorter wavelength than warmer light.
The wavelength of the light is especially important if you have plants or corals in your aquarium. Freshwater plants and symbiotic zooxanthellae in corals are relying on chlorophyll for their survival. Since plant chlorophyll absorbs light at wavelengths of 300 to 700 nm, not all light is usable light for this purpose. Different temperatures will provide varying degrees of useful light. LED aquarium lights with a Kelvin rating around 6400 hits a good balance here.
LED Aquarium lights with higher color temperatures produce bluer light that will penetrate the water more easily. This is worth thinking about in case you have a deep tank or organisms that are used to living at greater depths.
Here is a correlated color temperature chart:
|1000 K||Oil Lamps|
|1500 – 2000 K||Candlelight|
|1700 K||Match Flame|
|1850 – 3200 K||Sunset/Sunrise|
|1900 K||High Pressure Sodium|
|2700 K||“Warm” Compact Fluorescent|
|2700 – 3300 K||Incandescent Light Bulb|
|2700 – 6500 K||CFLs And Fluorescent|
|3000 K||Tungsten Halogen|
|3200 K||Studio Lamps, Photofloods, Etc|
|3350 K||Studio “CP” Light|
|3400 K||One Hour From Dusk/Dawn|
|4100 – 4150 K||Moonlight, Xenon Arc Lamp|
|4200 K||“Cool White” Linear Fluorescent|
|4300 K||Early Morning or Late Afternoon|
|5000 K||Horizon Daylight|
|5000 – 4500 K||Xenon Lamp/Light Arc|
|5500 K||Sunny Daylight Around Noon|
|5500 – 6000 K||Vertical Daylight, Electronic Flash|
|6000 – 7500 K||Overcast Sky|
|6500 – 9300 K||LCD Or CRT Screen|
|8000 K||Average Summer Shade|
|9000 – 12000 K||Blue Sky|
|11000 K||Sunless Blue Sky|
|20000 K||Open Shade In Mountains On Really Clear Days|