3000K Beats 6500K

[SantaMonica]

Well after three months of testing color temps, I've determined that 3000K out performs 6500K. It's not a huge difference, but enough to notice. At first they are about equal, but as the green hair gets over an inch thick, the 3000K continues getting thicker until it hits the acrylic wall (at 1.5"), whereas the 6500 stalls and rarely grows enough to reach the wall. So I'm ordering all T5HO 3000K replacement bulbs.

[kcress]

So redder is bedder?

[SantaMonica]

Appears so. I guess Chloryphyll A likes 420nm for a reason.

[Patrick Pending]

I read somewhere that you can only pump so much into the blue end before you reach saturation whereas the red peak of chlorophyll A can absorb much more energy. This is why the LED grow light panels have a much higher ratio of red to blue LEDs.

BTW: 420nm is the blue end I think you meant 680nm (red)

Cheers,

Pat. Pending

[Sly]

To add to the topic, I also have found that the redder the better. I got much better results from the soft or warm white CFL bulbs than I did from the cool white or daylight. The lower the kelvin the better.

I guess it all makes sense, really. When having an aquarium I was always told to replace the bulbs after a year whether they looked like they needed it or not. This is because over time, the spectrum of the bulbs shift toward red and this causes more algae to grow in the tank... Well since algae is what we want to grow in our tanks, then it makes sense to use redder bulbs...

[worley]

Yup, I can also confirm small, but noticeable increases in growth from lower colour temp CFL bulbs.