"Halogen Lights" are probably the most popular lights on the market because of their Small Size,
Lack of Electronics, Brilliant Light Output and Modest Price. However, there are two types of halogen
lights on the market today. Lights that utilize and internal quartz globe to house the bulbs in and those
that expose the bulbs directly to the water. The Magnum and AquaStar both utilize internal quartz
globes to house the halogen bulbs.
In order for a halogen bulb to burn it brightest, they have to maintain a bulb wall temperature of at least
250 degrees. Anything under that, and the bulb will start to turn black and will burn out. Lights that do
not use an quartz housing to house the bulbs are inferior and should be avoided.
The Tungsten halogen cycle is as follows...
Tungsten metal filament is heated by electricity to point of incandescence (emitting photons).
A few tungsten particles evaporate (boil off) from the filament and are carried away by convection
current where they combine with bromide vapor forming tungsten bromide.
If the glass (quartz) wall is above 250 degrees centigrade, then tungsten bromide particles will not
adhere to glass. Lights such as the Magnum and AquaStar use an inner quartz globe to house the
halogen bulb(s) in which keeps the bulb burning hot and bright!
They continue to circulate in the hot gas envelope by convection current and when they come back
close to the hot filament the particles reduce back to tungsten metal which is randomly re-deposited
back onto the filament thereby releasing the bromide vapor, and the whole process then repeats itself.
If every tungsten particle happened by chance to land back exactly where it came off, the filament could
last forever. But, they don't and eventually some parts of the filament get thinner and eventually burn
out, so good news is filament life usually is double over common incandescent bulb.
For the Tungsten halogen cycle to work, the bulb has to be on long enough to heat up completely and
keep the glass at over 250 degree centigrade. Any area inside the glass envelope which is lower than
250 degrees will attract tungsten bromide particles and the tungsten molecule will revert and cling tightly
to the cool areas on the glass and cool internal supports thereby causing the Tungsten halogen cycle to
fail. Therefore, exposing the bulb directly to the water will cool the bulb wall temperature, the halogen
cycle will fail and the bulb will gradually turn black and fail.
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