# Reducing Light Levels



## greg (Apr 29, 2012)

I've seen many discussions about methods to reduce light levels, while keeping the existing equipment - raising the light, dimmers, egg crate on top of the tank, applying tinted film on tank glass or on plexiglass bulb protector, etc.

Here's a very easy method I came up with to reduce my light level by 50% as measured by a par metre. Simply place a piece of black aluminum screen over the reflector. I was shocked by the result because when viewed with the eye, the screen didn't seem to obstruct the reflector by a significant amount. The light in question is a Hagen Glo which has a decent reflector. I would assume that the results would be less effective for a fixture with a poor reflector.










I had initially intended to use a method described by others and as pictured below - placing screen material across the bottom of the fixture. However I was disappointed that this only reduced the light intensity by 20%. Who would have guessed that placing a filter over the bulb which also filters reflected light, is much less effective than just filtering the reflector.










An added bonus is that you don't see the screen when the light is in position using the first method.


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## Mlevi (Jan 28, 2012)

That speaks volumes about the role of a good reflector in a fluorescent setup!
If covering just part of the reflector dropped the PAR by 50%, then I'd love to know what the difference in par would be between reflector and no reflector.

Al.


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