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Re: Hanging pendants vs closed cover

"Wright writes:

> The tank is not free space, and your lamps -- even MH -- are not point
>  sources. Light that you manage to get coupled into the tank through the
>  surface stays inside, like a light pipe, until it encounters some
>  absorbing/refecting surface.

It has been my experience that even a tank with nothing in it  but water and
gravel can be a significant light source for an entire room.  Light manages
to come out of it all over the place.  The reflectors on most light
situations are not nearly as focusing as a spot light, or even a typical
flashlight, where the bulb is buried way back inside a concave dish.

Bob Dixon"

I recently replaced 3 - 175W metal halides (hanging pendants - 525W total)
with an enclosed hood containing 6 - 55W CF tubes with good reflectors (330W
total) (AH Supply). Dropping from over 4 w/gal down to 2.5 w/gal has not
appreciably affected the growth of my plants nor detracted from the visual
impact of the tank.

Maybe it has to do with the fact that the better relectors that came with
the AH Supply units puts more of the light where it should be. But I do
notice a BIG difference in ambient light levels in the room. With the
pendants, there was very little need for other lamps in the room - indeed,
the GLARE was annoying and a pain. I was used to it but if I had company
over in the evening I usually had to turn off the tankk lights after a few
moments because people tended to want to put on sunglasses - the spill over
and glare was very bad. With the fully enclosed hood containing less total
watts but better reflectors, I have to use reading and general illumination
lamps in the room during the evenings. The aquarium looks wonderful, but it
no longer DEMANDS attention and you don't have to squint or shield your eyes
when sitting in the room. Now, it just "glows", not "glares".

Open top tanks with hanging lamps are nice, but there are viable resons to
keep the lid on.

James Purchase