Lighting Spectrum Questions.

[ahmed_iAM]

I recently noticed that many of the companies that produce lighting do not provide the correct spectrum of blue lights. Metal Halides and the sun tend to emit four wavelengths over the others. 410nm, 434nm, 486nm and 656nm. This is essentially the emission spectrum of hydrogen. The companies tend to put 450 or 460nm blue in their LEDs. I know that Ecotech now has more of the 440/450nm in the XR30w Pros. Is there a proven reason for putting the 450/460nm, and has anyone on here done a comparison of the 450/460nm vs the 410nm/434nm? Thanks.

[jedimasterben]

So you're saying the sun emits 410nm, 434nm, 486nm, and 656nm? The sun emits across the entire visible light spectrum at almost the same intensity, with a little more green and less red and violet, extending far past the visible spectrum into UV and IR.

Zooxanthellae use pigments for photosynthesis - chlorophyll a, chlorophyll c2, peridinin, neoperidinin, dinoxanthin, diadinoxanthin, beta carotene, and a few others. See Photosynthetic pigments of symbiotic dinoflagellates (zooxanthellae) from corals and clams by S.W. Jeffrey and T. Haxo: http://www.biolbull.org/content/135/1/149.full.pdf

Chlorophyll c2 content is around 10% that of chlorophyll a content, except in clams, which have 30-60% as much chlorophyll c2 as a. They also contain lots and lots of peridinin, mostly in PCP (peridinin-chlorophyll protein complex), which shifts the absorption peak of chlorophyll a to around 440nm and having a second peak near 500nm. Chlorophyll a by itself absorbs strongest in the 430nm and 660nm ranges, with chlorophyll c2 absorbing almost solely in 450nm, with a few small shoulders at 580nm and 630nm. The rest of the accessory pigments fill in the blanks, essentially, which allows corals to use almost the entire visible light spectrum for photosynthesis, though the peaks of chlorophyll a, c2, and PCP have the highest absorption efficiency (able to catch more photons).

The Radion does not use 440nm, Cree does not bin their LEDs below 452nm, Ecotech continues to say that they are lower when it is not possible for them to be and have been corrected many times.

This article contains a lot of information on lighting for corals, and talks specifically on the use of LEDs. http://www.advancedaquarist.com/2012/10/aafeature


Up until the last couple of years, violet-spectrum LEDs have been not only uncommon, but extraordinarily expensive (in the order of $30-100 each chip, with very low flux). Blue LEDs are dirt cheap to produce, and therefore other LEDs that use phosphor to change their emission spectrum from blue to, say, green or red, are in the same boat, but there are no phosphors that change blue to violet, so those LEDs have to emit that light from the get-go.

Even today, violet LEDs are much more expensive than royal blue LEDs, especially for higher flux. Most violet LEDs from China are around 15-20% electrically efficient (so if they use 2.5w of input power, they emit 500mW or less of light), whereas even Chinese royal blue LEDs are in the 30% range (emitting around 700-750mW of light at 2.5w input). Modern royal blue LEDs are surpassing 50% efficiency at higher input power (the Luxeon M at full current uses 11.5w of power and emits over 6750mW of light, which is ~59% efficient), and modern violet LEDs (such as the Luxeon UV) are over 40% efficient for their 405nm, 410nm, 415nm, 420nm, and 425nm chips, peaking at over 1,200mW of output at full current. Cost on the Luxeon M and UV are nearly the same, though, so while the Luxeon UV are output and PAR monsters, so are the Luxeon M, which outputs more total light for the same money.

As technology continues to move forward, LEDs will have higher and higher flux at lower overall prices across their entire catalogs, so violet LEDs will make more sense to use alongside royal blue and blue in time.

[solarwrx]

i think my mind just exploded ! LOL but i got the idea.

[jedimasterben]

LOL, it's definitely a lot to take in, and to think that that info just barely scratches the surface!

[ahmed_iAM]

Thank you for that information. I was basing this around the fact some metal halide peaks and the suns peaks tend to correlate around those values. The sun emits the yellow spectrum because the nuclear fission of helium which emits strongest at 450nm, 500nm, 501nm, 588nm. Though the sun doesn't only have those two gases, those two are in greater number than the rest.

[tkeracer619]

Just because a lightbulb peaks in a certain area doesn't have any relation to what the corals need. Radiums, long regarded as the number one halide for aquariums got its start as an accenting bulb for buildings. It was supposed to make buildings a pretty blue color, turns out it grows coral like crazy.