Re: [GSAS-Member] Speaking of lights... anyone using T5 HO fixtures?

["Doerr, Jesse" <Jesse.Doerr@fei.com>]

> (My Physics teacher would be glad to know that I occasionally use
> the "Inverse Square Rule" for light intensity; 2X the distance from the bulb
> and get ¼ the light intensity.)  For example, I have a 45 gallon tall (24"
> deep) and a 30 gallon long (16" deep); both tanks are 36" long.  To get the
> same light intensity to the bottom of my 45 gallon tank that I have in 30
> gallon aquarium I need 225% more output!  

Roy, this is true if you were using single bulbs to light your tank, but the 
situation changes slightly when you start using florescent tube bulbs.  With a 
long bulb your light intensity drop off near the center would be closer to 1 / 
Distance.  So if you doubled the distance you would only get half the light.

When you start factoring in the effect that reflectors and the water itself has 
on the light though, it all tends to get a bit... messy.  

But the general idea is correct: the deeper your water the more light you need. 
 And all things being equal this would mean needing a higher wattage bulb.  But 
you can still do a lot to improve your efficiency and penetration with better 
reflectors (and on LED lights: adding lenses).

Cheers,

Jesse 

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