Re: [APD] Re: help with finding inexpensive metal halides?

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

Arc lights such as fluorescents and MHs don't have a
continuous spectral output. They output is made up of peaks
and valleys at diff frequencies (colors). Diff combinations
of peaks and vallies can yield the same K rating.

Generally, as the color temp goes higher, the great the
amount of light output towards the higher frequency (high
energy) end of the spectrum realtive to the other end.

The light spectrum, from lower to higher frequency (energy)
is infrared, red, orange, yellow, green blue violet ultra
violet. Way past violet you have xrays and beyond those the
really high energy photons that make up gamma rays.

[In truth, the whole thing with color space and light and
perception is much more complicated than what I just
wrote.]

With the light bulbs for aquaria, genrally we're talking
about diff overall tones of white. 

Scott H.,

--- Nicolas Munro <nmunro at qld_yokogawa.com.au> wrote:

> Jennifer, try ebay - Lots of variety there and much
> cheaper in most cases.
> 
> 
> I have 10k fluros at home and a 5.5k fluoro which is very
> orange in 
> comparison. What is the difference between 10k and 20k
> light or even 20k 
> and 5.5k. 
> 
> I know the technical difference but I'm wondering what
> people feelings 
> and preferences are?  I want to grow fresh water plants.
> 
> =Nick
> 
> 
> 
> Jennifer Malmquist wrote:
> 
> > I have a 120 gallon planted tank lit with two 250W
> metal halide 
> > pendants.  One bulb died this weekend and the other is
> looking dim so 
> > I started looking into replacements, as my LFS doesn't
> carry the bulbs 
> > I need.  When I saw that bulbs sold specifically for
> aquariums on the 
> > pet-supply websites go for about $100 each I tried to
> look around for 
> > alternative sources.  After doing some research on the
> Krib I have 
> > found that I should probably find at minimum bulbs with
> a CRI >90 and 
> > a temp of 5000K (at minimum, higher is probably
> better.)  It seems as 
> > though bulbs with a lesser CRI and temperature could be
> used (and 
> > would be just fine for the plants) but apparently would
> cause the tank 
> > and light in the room to be an unpleasant color.  The
> tank acts as a 
> > room divider between my dining and living rooms, so
> it's important to 
> > me that the light quality be pleasant.  The tank has
> very few animal 
> > residents (a few shrimp, one incredibly large SAE, one
> angel, a few 
> > otos, one pleco and finally about a dozen tetras) and
> plants are 
> > primarily swords, crypts, aponogentons, and anubias. 
> No fast growing 
> > plants because I'm lazy and don't want to spend the
> time on the 
> > maintenance.  :)
> >
> > If anyone out there thinks that I'm incorrect (ie, a
> CRI of 60-70 on a 
> > 3500k bulb would be just fine - these bulbs were much
> less expensive) 
> > and/or can point me to a source I would be very
> grateful.  Thank you!
> >
> > Jen
> > _______________________________________________
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> >
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