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Re: Lumens per liter

"Roger S. Miller" <rgrmill at rt66_com> wrote:

> Lumens are a measure of light as perceived by the human eye; plants
> respond to light in a very different way.  Maybe Ivo can comment on this,
> but I seem to remember from comparing across a number of commonly used
> fluorescent lights that the wattage rating of a lamp was about as accurate
> as it's lumen rating when you need to estimate the light's
> photosynthetically active light output.

I agree. This is in fact the main result of my exercise (posted at the
Aquabotanic site). Lumens correlate poorly with Watts. PAR (Photosynthetic 
Active Radiation), on the other hand, correlates well. Thus the wattage of 
a light bulb is a much better estimator of its PAR emission than its lumen

- Ivo Busko
  Baltimore, MD