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Re: Lighting questions

>   Hello
>    Could anyone explain to me the difference between standard T12 and
>fluorex fluorescent light bulbs? I was particularly interested in how to 

Never heard of "fluorex" if that is a brand. If you mean "flourescent",
than it is as follows: T12 is a notation for the diameter of the tube, in
eighths of an inch (T12 = 1.5" diameter). T8 is 1" diameter, etc... Because
of the way the flourescent light works, the smaller tube allows the bulb to
operate more efficiently, which is why the T8 size has become the most
common commercially. 

>translate the K ratings to lumens. Aren't these both ratings of intensity >or color ratings?

K (Kelvin) does NOT equate to lumens. Lumens measure light intensity,
Kelvin measures the color temperature, which is a theoretical number that
represents the temperature a black body would need to be heated to to emit
light of the wavelength in question. Basically a higher Kelvin ration means
a bluer light. Daylight is usually quoted as being in the 5000-5600 K range
(note that Kelvin is NOT measured in degrees), but the actual number varies
with your latitude -- farther North/South from the equator gets a bluer,
and thus higher color temperature light.

> Also the difference between Halide and HID light bulbs. The
>more I read the more confused I get.lol

Halide lights ARE HID bulbs. HID stands for High Intensity Discharge, which
is a fancy way of saying that they are arc lights that use an electric arc
as the primary light source. Various materials are put in the arc tube to
create the different kinds of HID lights such as mercury vapor (MV), metal
halide (MH), and sodium vapor (usually HPS for High Pressure Sodium,
although there is also a low pressure sodium lamp). MH is typically best
for use with aquariums since it gives the best spectrum. HPS is sometimes
seen on parking lots, and it gives a bright yellow/orange light. The deeper
orange lights are the more efficient low-pressure sodium lights. MV gives a
distincly blue-tinged white light, and MH gives a daylight-like white light
that has varying degrees of blue to it with the specialty aquarium bulbs
you can get. A good example of a blue MH bulb would be the 10,000 - 20,000
Kelvin bulbs sold to reef keepers.

HID bulbs are famous for the super high intensity light and their high
efficiency. low-pressure sodium lights are the most efficient, followed by
HPS, MH, and MV in that order. T8 flourescent lighting is typically quoted
as being in the slightly-below MH to slightly-above MH range in terms of

There is also PC or PCF lighting (Power Compact Flourescent), which is
basically an extra powerful variant of regular flourescent lighting. It is
said to have similar efficiency to T8 lighting in most cases.


Waveform Technology
UNIX Systems Administrator