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Re: Algae and Incandescent Lighting



Tom Wood writes:

> Dennerle claims that algae prefers lighting with a blue
>  spike while plants prefer lighting with a red spike in the spectrum.
<snip>>  Incandescent lights are high in red and low in blue, at around
3000K.<snip>

Don Dixon misinterpreted:

Okay, here you are saying that incandescents are better for vascular plants
than for algae because they have low CRI temps.

I respond:

"I" didn't make ANY claims that incandescents are better for vascular
plants. As I said in my post, the Dennerle company claims that light sources
that are high in red are better for plants and worse for algae, which do
better under bluer lamps. CRI isn't part of the discussion at this point. I
was merely commenting that the Dennerle literature seemed to be
corroborating Matt's experience when the algae in his tank died back under
incandescent lighting, which is higher in red.

I wrote:

<snip> The
>  color rendering index (CRI) of most low light temperature lamps is not
good
>  compared to lamps in the 5000-6500K range lamps.

Don misinterprets again:

Now you are saying lights with low CRI temps are NOT good for vascular
plants.
Am I confused or are you?

I respond:

You are. I didn't say low CRI lamps are not good for plants. I said low
Kelvin lamps tend to have low CRI. (See the excellent post in this thread
from Ivo Busko though)  So if you are going to provide lamps that are high
in red to please the plants, it helps to add some lamps that are high in
blue to please your eyes. (Unfortunately this would also please the algae,
so we are back to square one again.)

Tom Wood
Austin, Texas, ya'll