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Re: Lighting and Lux

> Diane Brown:

> To compare different lamps and light output to plants in different
> tank
> setups, I'd think it would be useful to have two parameters:  lumens
> or lux
> or whichever light quantitation units are most appropriate at varied
> distances from the lamp in air, and then how that decreases once the
> light
> enters the water.  That way, you could calculate how much light bulb
> "x"
> gives when 2 inches above the water surface of a tank with 12 inches
> of
> water in it, and compare that to bulb "y"  held 1 inch above a 19
> inch deep
> water column, to see if x and y are comparable setups.
> (Of course, that's still only dealing with the single dimesion of
> depth,
> and doesn't take into account the surface areas and how the light
> intensity
> disperses over the area of the tank, or the photosynthetically
> available
> fraction of the light, but it might be more useful than watts/gallon
> alone.)

And turbidity.  Don't forget turbidity.  Micro bubbles in the water,
algae spores, detritus, etc. even if not easily visible to the naked
eye, absorb or disperse light.   :-)

More than watts per gallon, lux, lumens, or distance, my Rubin affects
how much light reaches many of my plants.  Can we plug "shading" into
the ideal formula?  ;-)

Meanwhile, Tom is still using PC bulbs that are years old.  So let's
get age factored in (bulb age, not Tom's).  ;-)

Watts is something most bulbs have printed right on them.  All the rest
of the info is hard to come by.  Some of it darn near impossible.  So
even if we had a formula, who could use it?  I'd like to know what some
good candidates for formulas are (why assume there will be one best)
but I treasure useful means for setting up and operating tanks,
especially ones that don't require expertise -- for myself, I can buy
lots of watts, but any expertise is borrowed.  

Reading by AH Supply aquarium light,
Scott H.

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