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Re: Watts, Lux, Lumens

Date: Thu, 17 Sep 1998 00:49:04 -0700
From: Mark Stahlke <mstahlke at denver_infi.net>

>As I studied different flourescent bulbs, It occurred to me that
not all
>watts are created equal. 

Excellent observation. 

> Would a formula based on lux or lumens per unit area be more
>than watts per unit area? 

Yes, but sometimes lumens are hard to find specified and lux (lumens
per square meter) depends on your specific setup so it can't be
spec'ed by the bulb vendor. 

The ideal situation is to know how what range of lux is needed for a
specific plant you want to keep (Allgayer and Teton have a table in
their book) and, using a luxmeter (about $130), select lighting,
reflectors, distance, lack of shadows, etc  to produce that lux
value.  Obviously, not a useful way for the average aquarist to
select lighting. And it doesn't make a good rule-of-thumb. 

So, about the best general advice is "watts per gallon" with all the
usual disclaimers, caveats, IMHOs, YRMVs and other weasling. 

See my web page for more details and explanations of the various
lighting terms. 

George Booth, Ft. Collins, Colorado (booth at frii_com)
  Back on-line! New URL! Slightly new look! Same good data! More to