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Re: Aquatic Plants Digest V4 #1263

It was written:

:I have two 13 watt PC from AH supply in a 10 gal hood. Both lamps and
ballast are enclosed in the hood and sitting on a glass lid.
All that AH recommends is holes drilled in the ends with some vented
that they supplied, and raising the back edge about an eighth inch.
I wouldn't consider it to be "hot." and I wouldn't waste my time or
putting a fan on it."

The amount of heat produced by a flourescent is about 80% times the
wattage.  Whether you tank can tank the added heat and whether the heat
is absorbed into the room without being absorbed by the water is
function of the hood setup, use of fans, ambient temperature, etc.  The
type of flourescent doesn't make that much difference.  Yes, a number
of VHO setups use fans.  Consider a pair of 2 foot long VHOs.  That's
nominally 150 watts going into the bulbs and about 120 watts of heat
coming out.  Its not the type of flourescent that dictates the need for
cooling, its the wattage, which a measure of heat produced, and the
ambient temperature that are primary factors.  The efficiency from one
lamp to the next does not vary radically compared to the overall rate
of heat production -- if one lamp, say 96 watts, is 19 % efficient and
another is 22%, they still produce pretty much the same amount of heat,
78 watts and 75 watts respectively.  AH ballasts have power factors of
.9. So, for a 96 watt setup, the ballast only gives off about 10 watts
of heat.  If the ballast is out in the open, much if not most of the
heat goes directly into the air without going directly into the tank.

Scott H.

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