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Im looking at a light fixture for my aquarium. My question isn't about the LED's as far as quality, penetration, etc.

This light has 430nm, 460nm, 630nm, 660nm, 390nm, 850nm, and 16000k lights.

The blues and the 16000Ks are no question of course. The reds I am a little curious about, from what I have uncovered, it seems that the 400nm range is most beneficial for chlorophyll A, and 600nm range are beneficial for chlorophyll B. Also from what I have uncovered is that the blue range is the most beneficial for coral growth, but right behind it is the red range, so how beneficial is it?

But the UV and inferred is what I really want to know about. I know that UV can be beneficial for a reef, and they won't be powerful enough that I'll be sterilizing the entire tank or anything. Not to worried about that, but any info would be appreciated.

The real question is about the inferred. Any thoughts, help, anything?
 

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Basically, from what I understand is no one LED can produce the full spectrum that a coral needs long term, each LED has a very narrow bandwidth of light that it produces. Which is why DIY LEDs with groups of different spectrums are far more successful than most of the fixtures out there.

420NM describes the length of the wave I seem to remember 420 and 456 being desireable blue actinic colors......, 10,000k describes the color temperature 6000 is yellowish 10000 is whiter 14000+ bluer... Don't ask me what the dirrect compairison is, especially with LED.

Everything I have learned in the last 25 years being around reef tanks is a 6500k light is about the optimum for coral growth, but it encourages the butt ugly brown coloration that everyone hates to see these days. The more blue/purple the better the colors of the coral but the less par value per watt and less grouth. 10k-14k halides were a comprimise between growth and color, especially with actinic suppliments. 6500k is closer to the actual color temp of the sun, obviously the yellow don't make it into the big blue and 20k is closer to deep water blue penetration. (okay maybe not so obvious)
 

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There are some interesting ideas floating around out there about LED lights, and particularly which ones to use.

The best I can tell you is that, like all things reef tank... we want to mimic the good things of the natural reefs as we can right here in out own personal tanks.

I say that as a precursor because there are a lot of available LEDs out there that put out spectrums not commonly known to natural reefs.

Red colored LEDs are a good example of this. In nature, as the light enters our atmosphere in is slightly refracted and the light slows down. Once the light hits the surface of the water, it again is refracted (bent) and the speed of the light is again slowed. This time, it is much more drastic, and colors rapidly drop off the spectrum, the first of which is Red.

I remember it as Mr. Roy G. Biv (Red Orange Yellow Green Blue Indigo Violet) Red is the first color to go, and that spectrum is not typically found at the depths of most reefs. This is also why our reef fish haven't evolved the ability to see red and using a red bulb at night will allow you to see in your tank but wont allow your fish to see you ;)

As far as UV is concerned, I think you hit the nail on the head already... UV light sterilizes stuff... it does this by breaking apart the DNA. that being said, coral produce pigments to protect themselves from this radiation and color up more when exposed to it. In short, some UV is good... but to much is deadly. UV LEDs should only be used with extreme caution, and probably best done by professionals. Do your research on them before trying them out.

Infrared is another form of light radiation. Like UV, it is not visible to the naked eye. However it is on the other side of the spectrum (the red side). I have to admit that I haven't done any research on using infrared LEDs over a reef aquarium, but I think it would be risky as well... Keep in mind that there are all sorts of radiation including xrays and microwaves... and I don't think anyone would ever suggest using either of these on our tanks.

I am curious if anyone is using infrared LEDs and what they might have to say about them. If it wasn't 11pm and I wasn't already working on multiple projects I probably would look it up myself... but its is... and I am... so I will let someone else do the leg work on this one :)

I'm happy to tag along on this subject :jester:

Happy Reefing! :victory:
 

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Too many comments above are basically false to start listing each one, but for starters a white LED has a more continuous and smoother spectrum than any halide wishes it could have. The halide might produce more UV-A (white LED's don't produce UV), but the halide will have jagged peaks and little color beyond 600nm. Sorry, been building LED fixtures for a few years and own a spectrometer, so I'm just trying to get the science straight so people can make informed decisions.

However, a bigger problem is that LED fixtures range from excellent to junk given that so many asian makers are jumping into the market. They can slap dozens of cheap LED's in a fixture and sell it for a few hundred dollars and in most cases it will work, but not to any optimum.

All the funky colors you've been seeing are the results of DIY'ers playing with different colored LEDs to get different effects. Has nothing to do with growth.

Corals utilize blue light for growth. Primarily around ~420-480nm, although the spectrum may be a bit bigger or a bit smaller depending on the biologist you talk to. All however will agree it's blue light that allows metabolic growth, and it centers around 450nm. There's very little yellow / red light utilized because there's not much of it as you go deeper in the ocean, and symbiotic algae in corals doesn't need internodal stimulation like houseplants do. If you put a sodium vapor lamp over your tank your corals will not grow well because they can't utilize yellow/orange light. Nuisance algaes however might be able to because they are not a symbiotic algae.

Biology lesson over, but the biggest advantage with LED's is even the mediocre ones produce lots of blue light because LED's are very efficient at producing 450nm (deep blue or what we call 'roya') light. Color temps should be ignored with LED fixtures because they do not utilize the same spectrum that halides due and hence a 14k LED light won't look a thing like a 14k metal halide. You really need to see the fixture in a reef store, or see it recommended by other reefers who might have pictures of it. All the really high end Reef lights have certain things in common. Mostly they emphasize blue, or two colors of blue and white. 400nm (UV-A) is *sometimes* used in lights to produce some additional colors along with far red (660nm). In my opinion these are the least factors you need to be concerned with.

Far red, which is 660nm and beyond can stimulate flower growth in terrestrial and fruiting plants, but has never shown to be a benefit to corals. One study I found showed it shutdown growth in acropora, likely because red light tells the coral "hey dummy, you're growing above the water". I don't think infrared it utilized by any organism other than to keep warm.
 
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