Date: Fri, 31 Mar 2000 12:29:31 EST From: EdwardK674@aol.com To: cp@opus.hpl.hp.com Message-Id: <aabcdefg955$foo@default> Subject: Degrees Kelvin
In a message dated 03/31/2000 4:39:18 AM Eastern Standard Time,
cp@opus.hpl.hp.com writes:
<< thought the light specs were impressive. They claim a 200 watt
light equivelent, Tri-phosphor bulb with a color temp of 4,000
degrees kelvin, CRI: 84, Lumens of 2,700. I have no idea of what CRI
is, an >>
Hi Stephen.,
One of the other possible options would be to order a prewired ballast and
endcaps and build a custom lighting system. I'm going to do that with a small
reef aquarium. Additionally you can order from aquarium magazines, reflectors
that can increase the amount of lighting reflected down to the plants.
I couldn't find any refrences in my Plant Pysiology Text about degrees Kelvin
and plants however one of my reef books (The Modern Coral Reef Aquarium Vol 1
by Fossa and Nilsen) has a good explanation. The higher the Kelvin number the
"whiter" the light with the violet, green and blue spectra prevailing. The
book also refers to natural sunlight being about 5800 K with variations
depending on time of day and weather conditions from 2500 K to 30000 K).
Personally, (as with reef aquaria) I would mix several different bulbs to try
and obtain as balanced a spectrum as possible. CRI (Color Rendition Index)
refers to how well the bulbs match sunlight in demonstrating colors. The
closer the CRI is to 100 the better the "true or natural" colors are
demonstrated.
Ed
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