Can someone explain what the "K" means when talking about lights?

NJ Devils Fan

#1 Devils fan
Oct 28, 2002
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I have seen in the catalogues and heard people say things about have bulbs like a 40 watt 6500K bulb. What does the number and the "K" mean after the wattage?
 
it's the color temperature of the light...natural sunlight is around 5000-6000K...the lower the K, the more red the light, the higher the K, more blue.
 
K is Kelvin Power. Exactly as the other person suggested...

example: 50/50 corallife bulb:
rated at 6000k daylight and 7600k blue actinic

Mid day tropical sun is 10,000k
High intensity 20,000= simulates deep oceans

Pure actinic blue light= 7100k

Trichromatic= 6500k full spectrum light
 
K, with regards to lights, stands for Kelvin, which is another temperature scale much like Fahrenheit and Celsius. If a theoretical black body (never really clear on what that might be) is heated to given temperature Kelvin, it theoretically emits light of a particular color. That color is then described as being that "color temperature" in degrees Kelvin: 6500K, 10000K, 4500K and so on. Higher K is bluer (cooler) lower K is redder (warmer). Like RTR said, it has nothing to do with intensity: its a technical description of the color of the light.
 
I dont know? Why dont you order from Bigals? you will find the bulbs to be about 10-15 bucks each for the best ones...
 
Originally posted by NJ Devils Fan
So could I just go to home Depot and get like a 100 watt bulb or would I have to get a special bulb from my LFS with that Kelvin Power rating?

All light can be described as having a color temperature in Kelvin, including the ones at the Home Depot, even if its not stated explicitly on the box (sometimes is sometimes isn't). You might be able to get this info on the manufacturer's website or some other resource (there are, for instance, articles that index all this stuff for hobbyists like us). If you don't want to deal with that, look for "natural", "daylight", "plant", or "aquarium: -- they're all there somewhere. Its only really significant for plants as far as freshwater goes, after that its personal preference.

And instead of the hood, why don't you just put a regular table lamp next to the tank? I had a little IKEA lamp there before the moonlight was installed.
 
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