Re: Lighting and Lux

["Wayne Jones" <waj at mnsi_net>]

Scott wrote:
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John T. Fitch reminded us of his analysis of Amano's lighting:


> . . . a
> few
> months ago, I did an analysis of the lighting used by Takashi Amano
> in the
> tanks shown in his 3 vol. series, Nature Aquarium World.  It turns
> out
> that. . .
> the
> lighting he uses is nearly proportional to the square root of the
> volume.

This analysis used watts as the light-level quantity.  Given the
relative constancy of the density of water
(at least in liquid form ;-)   ), that would translate into a watts per
gallon heuristic.   But note in the analysis

http://www.fitchfamily.com/lighting.html

that the there's a pretty good scatter of the points in the chart --
the rule of thumb, as we expected, relies on a really big thumb --
"plants need *roughly* that much light."

Given what we don't know (not just me, but what other, more expert
folks report to not know, what data isn't readily available, the limits
on combinations of tank sizes and bulb arrays that are practical, etc.)
-- given all that in the search for the right level light, I think we
still come back to the rule of 1-2 watts/gal for slow grow and roughly
3-4 for rapid growth with CO2 injection.  But the rule will only get
you into the neighborhood of right light.  Only your personal
experience can get you to the address(es).


Scott H.

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That article is not really plotting the lighting requirements of tanks
but the efficiency of short verses long lamps. Also since the short
lamps are less efficient he has to crowd more lamps in his fixture which
results in even greater efficiency losses. If Amano was using PCs he
would not be using so many watts on his small tanks. This watts per
gallon rule should only apply to linear fluorescents.

Wayne