Old Bulbs = Algae

[chris88]

You can't really compare Nm to kelvin. Red is from 650-700nm but that doesn’t correlate to a Kelvin tempter. A lower Kelvin light will have more red in its spectrum but that doesn't mean the bulb is going to look red. 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 which makes the color look white because of the way they blend. (6,500k – 14,000k)

[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.

[RuGlu6]

My T5 bulbs are 3+ years old. Replaced only when burnt out.
Have 6xTek T5.
My tank has almost non existent algae.
My SPS have VERY nice color and growth I have Pink, bright green, blue tip Dual Color SPS and green tip as well.
So go figure.

Low bio load (only 3 fish in 65 gal tank ), high ORP (with high air flow) air driven skimmer it is constant just over 450. Second skimmer is Deltek 600 HOB.