Re: [APD] Lighting

["S. Hieber" <shieber at yahoo_com>]

What kind of lamp and bulb is this (brand/model)? It very
well might be operating normally, designed to withstand the
temperatures involved.  So you might not have any problem
here.  But I will offer some very general points that might
be helpful.

Some Very High Output straight tube fluorescents can burn
at higher temperatures than regular fluorescents.

Power Compact fluorescents and VHOs, because they are
higher wattage in a given space than normal or regular
fluorescents, give off more heat even if operating at about
the same temperature.  The temperature and the amount of
heat, of course, being two different things. You can have
something verh high temp but giving off relatively little
heat (like a match head) and you can have something running
much cooler than, say, a match head but giving off much
more heat -- for example a fluorescent bulb.  The higher
heat that a higher wattage bulb gives off can cause the
lamp that the bulb is in to be hotter than a lamp with
lower wattage bulbs. Metal Halide bulbs, which usually are
slightly more efficient than most types of fluoresent bulb
give off less heat at a given wattage but he heat is
concentrated in a smaller area, so the temperatures close
to the bulb are higher.

Even regular fluorescents work best, generally, when they
are around 120 -140 degrees F, which is about too hot to
touch (depends on your fingers ;-) but 140 degrees feels
pretty darn hot ). The ends of the bulb where the bulb
sockets are will be hotter than the rest of the bulb. It's
worth noting that the efficiency of the bulb is lower if it
runs too cool.

You can usually tell if a lamp is running a bulb at a much
higher wattage than the bulb designer intended by a rapid
blackening of the tube at the ends.  Whereas this might
occur after thousands upon thousands of hours of use in
normal circumstances, it occurs much faster if the bulb is
overdriven. Depending on how much the bulb is overdriven,
the blackening can occur within a few weeks or a few days.

All fluorescent bulbs give off roughly 65% of there input
energy as heat -- that might sound like a lot but
incandescents give off about 95% or more of their input
energy as heat!

Some lamps are better designed than others to shed heat
into the room. If the heat from the lamp is causing your
aquarium to get too hot, you can try one or more of several
things to reduce the heat going into the aquarium by
diverting more of it into the room:

Use a room fan to move more heat away from the aquarium
(this has the least impact in most ordianry situations but
can be the easiest to try).
Raise the lamp -- even a few inches can make a big diff.
Add a fan to the lamp or aquarium hood -- This is the most
costly and the most work but is the most effective.


Hope that helps,
Scott H.
--- Roy Quek <royquek at yahoo_com> wrote:
> Hi
> 
> I just bought a flourescent lamp meant for aquarium
> use and have just set it over my aquarium for about an
> hour. But after turning it on for just over an hour,
> the whole lamp is so darn hot! . .
> ANy advice from seasoned hobbyists who can help me out
> here? Or am i just worrying over nothing? Thanks


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