Lighting calculator - Amano style

[Ghazanfar Ghori]

Here's something interesting I came across. It's better
than using the 3Watts/G rule...

<a href="http://www.fitchfamily.com/lighting.html" target="_blank">http://www.fitchfamily.com/lighting.html</a>

[RTRJR]

I like that analysis...

Comments from Ivo?

[SCMurphy]

Watts per surface area, interesting, I wonder what watts per depth would show.

[RTRJR]

That is why I'd like to hear comments from someone who in-depth knows these points. Point source versus line source versus plane source does affect the computation. I remember from my time of playing with terrestials under lights that at some home-achievable point, the distance from the tube dropped out of the equation. I have always had the suspicion that this had some effect on the lower wattage needed for large tanks.

[Jonathan Kalmes]

I'm just going to try to confuse the issue even further here...

There are two other points that aren't really addressed (at least not directly) in the article. Water does absorb and reflect a certain amount of light. Also, the tank glass reflects light back into the tank. I believe that the amount of absorption is also logarithmic and I suspect the reflection from the glass is as well... if not directly, then at least indirectly due to the absorption of the source light by the water.

I would suspect that this is the reason that the graph in the article is logarithmic in the first place, due to the amount of absorption caused by the depth of the water in larger volume tanks and that the amount of glass that there is to reflect the light.

Just a guess though.

[Archie]

I think the guy did a good job at attempting to solve one of the most common problems found with keeping aquatic plants. unfortunately, i haven't seen Amano's books, but does he always plant the same stuff? i ask this b/c if his choice of plants is always biased to those needing high light, then what the guy says is true. if he varies his plants, for varying lights, then i am thinking a more in-depth analysis would be necessary, to prove this true.   
Also, if we really want to get technical, if there is canopy glass, then some light will be reflected, and also refracted so some of the properties of the light will have changed. Jon, were you talking about the canopy glass or glas from the sides of the tank? I think this would be a great thing for an aquatic plant enthusiast that is also a physicist.<edited><editID>Archie</editID><editDate>37961.0001851852</editDate></edited>

[Ghazanfar Ghori]

I tried a few different tank sizes in his calculator,
and IMO it comes out with appropriate lighting levels.
Better than using 3 W/G rule. Again, this is just a
starting point - can be tweaked to accomodate
medium light / low light tanks too.

[Marsha Finley]

Hey Folks!

Does color sbstrate have any effect? I rememeber seeing research on the growth rate of violets when grownin white vs green or terra cotta colored pots...

Just curious as to any observations you may have.

[Ghazanfar Ghori]

A lighting colored substrate will reflect a lot
of light back. It's effect on the amount of light
needed? Don't know if it would make a huge difference
or not. Anyone care to experiement?

[RTRJR]

But even my non-high tech tanks tend to be fully planted - other than some catfish tanks where it would not be appreciated - so reflection should not enter the equation very strongly. Perhaps immediately around a white sand beach?

Besides, I have very limited tolerance for light colored substrates. Several years of my poultry heath grit/crushed granite period soured me on light and bright.