Old Bulbs = Algae

[Myka]

Graeme, it is still interesting information that's kinda on-topic. the bulbs we use are usually "rated" at a certain color temperature, but if you use a CT meter it will say the color is much different. I don't fully understand why we see it as a different CT than the meter does? Must have something to do with the spikes in the spectrum over-powering our eyes maybe...?

Originally Posted by chris88

Just like a 10,000k bulb has a lot of green light, it doesn’t mean the bulb looks green. A 2,700k bulb will have a warm oranage-ish yellow hue almost like a candle light, while a 20,000k barely has any red spectrum in it and is predominantly blue. Most mid range bulbs have spikes in different spectrums...

That's why they are called "full spectrum". Some are "fuller" than others though. I think most people know that all the colors in the rainbow are in "white" light.