Watts vs. lumens, rule of thumb?

To: Aquatic plants list <aquatic-plants at actwin_com>
Subject: Watts vs. lumens, rule of thumb?
From: Cynthia Powers <cyn at metronet_com>
Date: Tue, 19 Nov 1996 17:33:34 -0600 (CST)

---------- Forwarded message ----------
Date: Mon, 18 Nov 1996 21:12:46 -0800
From: Mark Pearlscott <toy.fox at postoffice_worldnet.att.net>
To: Aquatic, Aquatic Plants Digest <aquatic-plants at actwin_com>
Subject: Watts vs. Lumens, rule of thumb?

There has been a big debate over Watts (power usage) vs. Lumens (light
output), and what is best for the "easy rule of thumb" (currently stated
as approx. 3 Watts per gallon).  The argument I hear is that the common
person is having trouble finding out the lumen rating of the bulbs they
are purchasing, and therefore we must settle with the Watts/gal guide.

Searching on the Web I found a post (from Aug. 1, 1994) by Joseph
Sellinger (reposted by George Booth due to Joseph having trouble posting
it).  This post is an extensive listing of bulb data (including
spectrum, length, watts, LUMENS, brand names/parts numbers, etc.). 
Though the lumens listed in the post are mostly initial lumens for the
bulbs, it seems as though the design lumens (which I would believe to be
closer to the actual readings) are not significantly lower.  This post
can be found on the Krib at:

http://www.cco.caltech.edu:80/~aquaria/Krib/Lights/fluorescent-table.html

My guess is that the bulbs (produced now) probably have not changed too
much in their output since (ones produced in) 1994.  Taking all this
into consideration, and assuming an average tank depth of 18", couldn't
we come up with a "Easy rule of thumb" for Lumens?

My thanks go out to Joseph Sellinger for the data he collected and put
together.
-- 
><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>  ><>

<><  If only we could dream like fish...     <><	Mark Pearlscott

><>  then our souls would be free...	     ><>	toy.fox at worldnet_att.net

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