[APD] Re: Lighting

["Daniel Larsson" <defdac at hotmail_com>]

Lief Brittan Youngs wrote:
>Is there a measurement that is best? 

Yes, there are better measurements than wpg.
Ivo Busko calculated PUR-efficiency, and I did
a Java-calculator where I input the spectrum, initial
lumens and watts and it calculates the bulbs
PUR-efficiency.

PUR-efficiency tells you in one number how
efficiently the bulb outputs it's energy in
the area of the photosynthetic action spectrum.

You can read how it's done here (last in the
article):
http://www.aquabotanic.com/lightcompare.htm


>(Kelvins, watts, etc.) It seems that what 
>was said is that the color of the bulb 
>doesn't really matter as much as the watts 
>per gallon. Is this true?

Both yes and now. Color in one number such
as Kelvin doesn't say a thing. But color in the
form of hundres of numbers like in a spectrum
tells you much. You can calculate how efficiently
the bulb converts watts/energy to lumens and 
with this effeciency  you can calculate how
well the spectrum conforms to the photosynthetic
action spectrum, which roughly gives you how
"hard" the bulb is hitting on the vital parts of the
plant ;)

You can send me spectrums+watt+lumens of
the bulb you would like to calculate PUR-efficiency
for. 

Ivo: If you're reading this, please contact me
off list. I would like to discuss the calculator.


// Daniel.
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