Minimum Light Threshold - The Planted Tank Forum
 
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post #1 of 4 (permalink) Old 05-03-2008, 05:44 AM Thread Starter
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Minimum Light Threshold

So im trying to understand how rex grigg's minimum light threshold works but am having trouble understanding how to use these numbers.

Quoted from rex grigg site:
"Now I know what you are thinking. I can do watts per gallon pretty easy. But how do I figure this LSI thing? Well find the surface area of your tank in square inches. Then take the LSI number you want to reach. Multiply the surface area by the LSI. Take the result and divide it by the LUX rating of your chosen light. I will admit that this system is not perfect by any means. But I think it gives a better idea than the WPG rule"

So my surface area is 124 inches squared.
The LSI i would like to reach is 30.
So 124*30= 3720
The LUX rating of the light: 2835
So 3720/2835= 1.31

So what excatly is this 1.31 is that my LSI?

thanks in advance.
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post #2 of 4 (permalink) Old 05-03-2008, 10:50 AM
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i have no clue, i go by wpg because it is good enough for most tanks (and i dont have any big tanks, and i have figured out how it works with small tanks).

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post #3 of 4 (permalink) Old 05-03-2008, 12:43 PM
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Judging by the formula, I think 1.31 would be the quantity of the given lamp you used in the formula needed to get to 30 LSI. Basically, one lamp with 2835 lux wouldn't be enough to reach 30 LSI. With that lamp, you're looking at 22.86 LSI (2835 lux divided by 124 inches squared).

I hope I didn't make you more confused! LOL

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post #4 of 4 (permalink) Old 05-03-2008, 07:06 PM
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Hi

The square root of 124 inches squared is 11.136 inches. That's a tank that's around 5 US gallons, I believe.

What are the gallons and the dimensions of your aquarium?

This Amano lighting calculator may be useful to help you figure you lighting needs: http://www.fitchfamily.com/lighting.html

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