Re: [APD] relative plant growing efficiency

["S. Hieber" <shieber at yahoo_com>]

Jsut rough cut -- it's a matter of efficiency and how awful the light color is that one can stand. You can HPS with very high efficincies -- Think of parking lot lighting. If you stay in the range of, that looks okay lighting, then you're going to be in the same neighborhood with MHS or fluorescents. The high power ones can let you pack more in a smaller space. The plants won't care about the color so long as they aren't mostly green in color, like a christmas bulb.
 
Therre are some arc-light bulbs that acheive over 80% energy efficiency -- however the light is all within a single very narrow band of the spectrum, sort of a fluorescent puke yellow.
 
The math, if one sat down to collect the data on the actual usable light energy and crunched the numbers, it would, I'm sure show a lot avariety even within bulbs of a given type, say, PCs. I wouldn't find the exercise useful for aquatic gardening purposes. To me it's like asking what diameter tubing yields the steadiest flow of CO2 and minimal permeation through the tube walls. I jsut pay the $10 and fill the tank when it's empty.

sh 


----- Original Message ----
From: Liz Wilhite <satirica at gmail_com>
To: aquatic plants digest <aquatic-plants at actwin_com>
Sent: Friday, March 17, 2006 1:17:10 PM
Subject: [APD] relative plant growing efficiency


I was asked a question that I have no idea how to answer but I bet a
gazillion of you can answer.  I was asked about the relative plant growing
efficiency of power compact fluorescents (i.e. the ones in something like a
Coralife fixture) vs HPS -- in other words if you had 250 watts of each type
which would:1) waste the most energy as heat and 2) grow plants the fastest.

After getting past the discussion about why any sane person would want to
grow plants as fast as possible, and the pitfalls of nutrients, CO2, etc., I
was left with this as a theoretical question.  And I have no clue what the
answer is.

Frankly, I'm now curious enough that I'd like to know what the
"equivalencies" are.  Stated differently, I'd like to know this:  I have 100
watts of power compact fluorescents.  For the purpose of growing plants how
many of watts of HPS, metal halides, LEDs and normal T-12 bulbs does it take
to match that."

Any takers?  Any guessers?
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