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Re: [APD] LED Lighting

Doubtful that each plant has the same favorite wavelength
but generally the green ones aren't favored, but reflected.

I'm not sure but I think the ultrabrights/superbrights rely
on phosphorescence or a something similar -- the emmitter
is doped with a chemical that glows when the diode is
emitting light. I would expect the range of wavelengths to
be limited by the type of doping used. With so many LEDs
required to be a sole light soruce for plants, one could
certainly have a wide range of wavelengths.  In fact,
mixing trios of red, green, blue might be a a more
efficacious way to create white light for plants. 

There is definitely an issue of light dispersion -- the
focus formthe LEDs tends to be very narrow unless the lens
is "fogged", which sharply reduces the effective light

This subject comes up about once per year. Each year the
prices drop a little bit. But they have a long way to go,
just like digicams ;-)

Scientific American had a nice article about the
superbrights about (I think) a year and a half ago.

Scott H.
--- Arild Madsen <Arild_Madsen at chello.no> wrote:
> Andy Lavery skrev:
> > Hi all,
> > 
> > I must say, I've truly enjoyed reading the archives of
> this list though 
> > I didn't find specifically what I was looking for; So I
> joined so I 
> > could ask a question.
> > 
> > Has anyone tried to use LED lighting to light a planted
> tank? I've been 
> > researching this for the last couple weeks - I can't
> find anyone who's 
> > done it (Well, there might be some dutch/germans - but
> my knowledge of 
> > those languages is lacking). But I've found plenty of
> LED moonlights in 
> > fresh and saltwater aquaria.
> > 
> > To test the theory, having an array of 6 luxeon star
> 470nm lights - I 
> > put them on my 2g planted tank. The tank glowed well
> beyond what the 
> > current 2 x 13w power compact could ever do. The fish
> definitely didn't 
> > appreciate it... I hope that was just the intensity &
> color.
> > 
> Do we know what wavelenght's the plants need to grow?
> One LED wil only luminate at one wavelenght, which would
> bee a good 
> thing i we knew the ideal wavelenght for the plants to
> grow.
> > I'm going ahead and ordering 20 ultra bright white
> (6500Kelvin) 5watt, 
> > 20 degree 10,000mcd LEDs, in order to truly test
> whether this could work.
> > 
> White LED's are a hybrid tecnology between a LED and a
> fluorescent lamp 
> and acording to what I have been told they will bee less
> efficient over 
> time compared to ordinary LED's.(limited lifetime)
> > Of course I've got doubts running through my mind, I
> have to wonder if 
> > 25w of LED light is too much in comparison to the power
> compacts 
> > currently on the tank. How best to space the LEDs to
> get good coverage 
> > (I'm sure that will be trial an error - but the
> 20degree 'spotlight' 
> > like output is going to make things difficult). I don't
> suppose of the 
> > lighting guru's here - I might have some answers?
> > 
> Godt nytt år / Happy new year.

S. Hieber

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