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Re: [APD] Aquatic-Plants Digest, Vol 25, Issue 55

Thomas Barr wrote:
> You still have yet to offer this empirical evidence you claim is better. Still all talk, no empirical evidence/anecdotal yeehaw. Say Bob has offered and better solution than you have. And I'm waiting to be proven wrong.

I didn't claim to have empirical evidence, I asked where that evidence 
is. It is you who are making the positive assertion that watts per 
gallon is the most useful way to determine required light levels. I 
asked what empirical evidence this is based on and you turn around and 
call me a "little physicist," and call the discussion "heehaw."

> The graph maybe useful to correlate PAR to Lumens to W/gal, but most folks still think in terms of w/gal, few aquarist around think in PAR/area.

I was able to show that lumens are more correlated with PAR than watts - 
at least for the bulbs listed at aquabotanic.com. That should be an 
indicator that watts per gallon is probably not the best way to describe 
light levels in a way that is useful for plants. Instead of accepting 
that you choose to say that it doesn't matter because "most folks think 
in watts per gallon." Did it ever occur to you that they think in watts 
per gallon because people keep telling them that this is the proper way 
to think?
> My issue with that is..............a newbie will know what a watt is and gallon is and be able to figure that ratio rule out pretty easily, but what about PAR? Lumens, CRI, all these technical units used for lighting?

Do you really think a newbie has more of a problem reading the lumen 
rating off of a bulb box than they do reading the wattage? I am willing 
to bet that lumens or watts are equally esoteric measurements to a newbie.

> My measurement is now now done. If I have issues with the lighting, then I need to focus on the plant species or the CO2/nutrients since Bob was able to do it with new bulbs.

And what are those measurements?

> This means far less variables than the method you are suggesting.
> And cost less, less work and produces a nicer tank in the long run.

You propose that not measuring anything other than watts per gallon and 
raising or lowering lights presents less variables rather than more? I 
can't believe you are being serious.

> Well if $$ is the issue here, good CO2/nutrients etc, less light(more is not better), using high efficency lights such as HQI's, PC's, T5's etc will go a long way. 
> You also just try it and see and make sure the plants are pruned the way you want, appear the way you want, and you can change the light time(oh! there's yet another variable!) or stagger the light pattern(Amano does this as do many folks for a high noon effect) to reduce light usage with higher watts.

This line of reasoning is not sound. Let's apply it to something else 
and see how it sounds:

Of course, what good are recipes? Everyone's oven is different, the 
ingredients are different brands, they may mix the batter for longer or 
shorter than someone else, who knows what the chickens that laid their 
eggs ate ... it's just too many variables to draw any useful conclusion. 
There's no point in trying to measure the flour exactly when everything 
else will just change the result anyway.

Jerry Baker
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