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Re: Aquatic Plants Digest V4 #1414

Danny ounsworth asked:
> Here is one for the lighting experts.  I'm putting T-8 lights in my
> new 55 gallon. I am wondering how ballasts achieve a ballast factor
> of 1.20 or 1.15. Do they just use more electricity than say a ballast
> with a 90% ballast factor?  And do the bulbs appear brighter just
> because they are being overdriven?  Do you need any special wiring
> for these high ballast factor ballasts?
> Danny
Ballast factor describes how well a ballast performs compared to a
standard ballast when paired with a given bulb.  It's just a general
reference -- it doesn't for example mean that the ballast is 20% more
efficient, just that it produces more lumens with the given bulb the
manufcturer used for the measurement.  One way one ballast might rate
higher than another is if one tends to run less amps through the bulb
and so run it cooler (and a longer life by the way) and less bright
while a second ballast runs it hotter.  Voltage differences can also
come into play.  Generally, a higher ballast factor gives more light
with a many but not necessarily all bulbs and runs them hotter and
burns them out quicker (depending on how well the bulb is built to
withstand running at higher temps on ballasts with high ballast fctors.

Hope that helps,
Scott H.

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