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Re: light intensity

Steve writes:

> Is 250W too much
>  light for a 60g tank thats 24" deep?  Hard to tell.  Its not as high a 
factor as the
>  smaller tanks, but still nearly twice what the 50g tank has at 2 
watts/gallon.   (the
>  reason I ask is that I'm currently setting up a tank like that, and after 
hearing the
>  discussions here, I think I have too much light)

It's not nearly as much as sunlight , and if you took a photographer's light 
meter into the woods and checked in the shade of the trees, you're still not 
as bright as that at the bottom of the tank.

>  I'm not sure that aquarium lighting falls off with the square of the
>  distance,
>  because there is quite a bit of internal reflection of the lights off
>  the sides of
>  the aquarium.  It may be something like depth^1.5, but I really don't
>  know.

A lot of light is absorbed by the water itself.  Perhaps not enough to be 
noticed, but it gets bluer fairly quickly.  I haven't really considered that 
before, but maybe a lot of extra blue would be better in tanks over 18".  Or 
maybe more red in order to compensate for the loss at the red end?  I don't 
know.  But even when you aren't talking about light through water, the square 
of the distance thing still applies.  Even with spot lights.

Bob Dixon
Cichlid Trader List Administrator