Re: NANFA-L-- spiral strip

Jerry Baker (
Fri, 31 Mar 2006 12:37:20 -0800

Todd D. Crail wrote:
> They can have the same luminosity as a "less efficient" bulb, but (and this
> is of note) offer absolutely nothing to photosynthetic organisms. That's
> why the spirals work great over fish tanks, as they have very little PAR to
> offer to algae, but don't expect much of them for plants.

Just a minor niggle: Daylight bulbs will have much more blue in them
than regular cool white or warm white bulbs. They will appear more dim
to us and brighter to plants (chlorophyll's peak absorption of light is
in the blue - 445um). That's why grow lights look so dim compared to a
regular light. PAR is just a measurement of the actual number of photons
occurring between the blue and red spectrum (sometimes referred to as
photosynthetic photon flux density). If you are using daylight spirals
over a tank you will be offering more PAR than if you use warm white or
cool white bulbs because the latter have almost all of their light
output concentrated in the yellow-green area of the spectrum - the least
usable to chlorophyll.
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