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Re: MHD Lights

> Alfred Heng <alheng at pacific_net.sg> asked:
> > How much heat does MHD lamps generate?  I am considering 2 150watt
> > lights for my new tank.
> I always get a giggle out of this question. Heaters and light bulbs are
> all rated the same, in units of power (either electric power consumption
> or heat generation). The amount of heat generated is equal to the amount
> of power consumed (although a small amount of the energy is actually
> captured by the plants and converted into stored energy in the form of
> carbohydrates). 300 watts of MH generates the same heat as 300 watts of
> FL lighting. There is a small difference in the amount consumed (and
> released as heat) by the ballasts.


I understood that the question refers to "how much heat a MH lamp releases
directly to the ambient". As you said, every single watt of electricity
consumed by a lamp fixture ultimately ends up in the form of heat, either 
as direct heat emission by the bulb/ballast, or as light absorbed and 
re-emitted as heat by the objects illuminated by the fixture (except, 
as you already pointed out, the small amount that goes into chemical 
conversions in plants). But the "light / direct heat" ratio provided by
different types of bulb can be very different, as in between fluorescents
and incandescents. 

Or did I entirely miss the point here ?

-Ivo Busko
 Baltimore, MD