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Erik's lighting results

I agree with Frank that Erik's survey results are thought-provoking and an
interesting contribution to the hobby.  I have some observations and

	First, the difference between the data from Amano's books and the
Usenet data is striking.  I've only read one of Amano's three volumes and
my recollection is that the smaller tanks feature a lot of stem plants
with very dense plantings that shade each other, and that the larger tanks
feature more moderate and low-light plants, with relatively little
shading.  If my recollection is true and his other books are consistent,
could the trend in Amano's data be a product of his unique style?

	Second, when I visualize a trend through the four data points from
commercial fixtures it parallels the trend in Amano's data, but is offset
downward by a factor of about 4.  Commercial fixtures I've seen are
usually single-tube lights, equipped with whatever tube is close to but
shorter than the tank the fixture will fit on.  So the trend (if there
really is one) is determined mostly by the *length* of the tank and the
wattage of standard flourescent tubes, not by area or by volume.  You
might create the trend in Amano's data just by using the largest 4
commercial fixtures (or a fixture with 4 flourescent tubes) that fit over
a tank.

	Third, the trend is reproducable, plus or minus a factor of 2.
So, if someone is trying to find out how to light his new tank, the graph
might suggest he use (for instance) 80 watts of light, and the data
indicate that people are using anything from 40 watts to 160 watts, right?
I think that would be generally realistic advise, but probably most people
would be looking for something a little more specific, for which they
would need to provide some more information.  Erik provided a list of
lighting factors, but (question for the list) what are the most important
one or two details they need to provide?

	Last, the data are plotted up in log-log coordinates, which is
great when you're dealing with something (like chemical concentrations)
that obeys logarithmic rules.  Is that the case here?  If not, then
log-log plots will sometimes compress data to create trends that aren't
evident in linear plots.

Roger Miller