Compact Fluorescent Spiral Lamp

[Proost]

05dr - I think you said it your self:

i have looked at tons of both commercial and aquarium specific bulbs (t12/t8/t5/linear pc/spiral pc/metal halide) in this range of k values and outside of some of the tri-phosphor daylight bulbs (not truly "6500k") they all look yellow to me.

Even thought they may more look yellow to you than a "bluer" bulb (10000K), I don't think it is fair for you to call it a "yellow" light. 6500K is approximately the color temp of the sun at the equator at noon. So, most people generally consider that a "white" light. There are a lot of us that prefer to see our plants or fish under a color light that is closer to nature. To me, the "blue" bulbs you prefer look unnatural, especially in a plant tank. It definitely is a matter of preference, but for ease of discussion sake we consider light that is close to the sun as white light. In fact many lighting companies list the 6500k twist bulbs as a "white light with a blue tint". So, basically, if you prefer more bluer light that is fine, many people do. But, I think we should call them that so that we are all on the same page when we describe the color of the light.

On CRI - Of course if a bulb has a spectrum that is very differnet than the sun the CRI is going to be lower. CRI = color rendering index, which is how closely a light renders color to the sun.

I see you do have the "Daylight bulbs", i apologize. The ones at my Home depot are from a different manufacturer. Interesting, I will see if I can get the info off mine when I get home.