benefits of adding violet uv leds?

[THE WOOKIE]

thinkig about adding a few to my fixtures. right now each fixture has 28 royal blues and 27 cool whites. would i notice a change by adding red green or uv leds?

 

[higorc]

Besides making some corals fluoresce/pop more? It's beneficial for photosyntesis...

 

[dannyp02908]

How about less hypothesis and more factual data? UV leds have been available for a little while. Long enough that I am sure people have tried them. Fixtures with red/green have been available for some time as well. Anyone have any documented proof that the "full spectrum" leds are better?

 

[JohnK]

What sort of documented proof are you looking for? In this hobby we get a lot of anecdotal info, but rarely much else.

Are you thinking spectual graphs, comparing PAR numbers, or something that would show impact on coral growth?

 

[newenglandreef]

There's no real evidence of UV's really adding anything. Many theorize that supplementing with a light with 420nm (like actinics) would be best. I run Vegas, which has pretty full spectrum. I had purple acro before adding actinics, which was brownish with very deep purple tips. I added actinic T5 supplements, and it turned a florescent green. Nobody knows why coral turns different colors in different tanks--so I don't think anyone can tell you what to supplement with for whatever goal. I can say, however, that plain old blue and white LED's grow corals like crazy in my experience.

 

[Flame Angel]

Matt Pedersen was at the meeting some months back and touched on LED's a little bit. He pretty much stated that the technology was still developing and the jury was still out. But just the basic blue and white were what was needed to sustain corals.

I am sure someone else that was at that meeting as well will chime in here a little bit.

I want to say that Marc Levenson had some input on this topic as well this past fall when he gave a talk on PAR.

 

[higorc]

Besides making some corals fluoresce/pop more? It's beneficial for photosyntesis...

Sorry... I didn't mean true UV. I meant 420nm spectrum. Which is close to the UV spectrum. But not UV. True UV would be under 400nm.

 

[LoveTheReef]

There are benefits.

Please look at some very good information here: http://aquariumdigest.wordpress.com/tag/led/

I am not affiliated with the blog or its writer -- just found a lot of good information that helps support (scientifically) my theories and my results with leds so far.

Sent from my SCH-I535 using Tapatalk 2

 

[inverted]

Sorry... I didn't mean true UV. I meant 420nm spectrum. Which is close to the UV spectrum. But not UV. True UV would be under 400nm.

It is my understanding, that there are no "true uv" leds in the aquarium market. They are all 400nm "violet" I guess "uv" must have sounded sexier than violet. Many SPS corals produce colorful pigments, in response to certain wavelengths and glow nice colors. These pigments are well studied because of their use in molecular biology and there are certainly pigments that respond to 400nm light. Probably not as bluer light, but some. So, if these pigments are desirable, then having some "uv" leds is good. Basically, violet and blue etc.. are high energy light, so, when there is a lot of it, the coral wants to block it and produces pigments accordingly. However, producing pigment takes energy and therefore stresses the coral, so, corals don' usually produce pigment unless they need to. The only other thing though, is our eyes can't violet light well, so, it is easily washed out by other colors. In other words, unless the light is very blue/violet dominant, you may not notice. Anyways, so, yeah, it can be beneficial, if you like that fluorescent look; it won't likely have any effect on health though and "true uv" would be bad, if you ever came across one. Even low levels of true uv light are shown to reduce rates of photosynthesis and high levels damage DNA.

 

[dannyp02908]

If low levels of true UV are harmful, then what about T5s and MHs? It is my understanding that both produce a little UV.

 

[inverted]

It is my understanding that both produce a little UV.

"very little". Well, technically halides produce more, but it is blocked by shields, very little gets through. UV is technically less than 400nm, some sources say 380nm. UV-A is the least harmful and goes down to 315nm. Down to 280 is uv-b and down to 100 is uv-c. uv-b and c are much more harmful. Water alone blocks much of the uv output too.

Anyways, here are some graphs. UV is on the horizontal axis on the left side of the graph, intensity on the vertical axis. As you can see, for the ATI bulbs that produce the most uv, for example, there is barely anything under 400.

ATI Blue plus

ATI Actinic

This review shows some shielded 150W HQI halides. There is a bit more, but nothing to speak of below 350nm really, so, still barely any UV-a even from the halides as well.
http://www.advancedaquarist.com/2004/5/review


For more detailed info, this article reviews UV and corals.
http://www.advancedaquarist.com/2004/8/aafeature

From it, there was review, plus an experiment to see how UV effected the photosynthetic yield of a montipora capitata.
This graph for example, shows the drop in production when exposed to mainly UV-A radiation.

 

[newenglandreef]

That's interesting that the Blue Plus peaks at around 470nm. I'm really starting to believe that the whole 420nm issue isn't an issue at all-and that the anti-LED people are just looking for what lacks in the LED spectrum to support their position. I really don't think we can pinpoint why certain corals are one color in one tank and another in a second tank (or part of a tank), which makes supplementation at this point kind of a fools errand.

 

[STiTCH87]

Chlorophyll A absorption peaks at 412nm. So 420nm isn't NEEDED, but it's right around where Chlorophyll A will be able to utilize light the best for photosynthesis.

 

[newenglandreef]

If we have ample useable light, which is the greatest with LED's (with the highest PUR per PAR), then sufficient absorption shouldn't be a problem. I wonder if that's the issue--too much PUR per PAR. Anyone know if there is any substance that filters just PUR from a wavelength? I'd test it out.

 

[STiTCH87]

Interesting theory... Wouldn't mind finding that out myself.

 

[inverted]

If we have ample useable light, which is the greatest with LED's (with the highest PUR per PAR), then sufficient absorption shouldn't be a problem. I wonder if that's the issue--too much PUR per PAR. Anyone know if there is any substance that filters just PUR from a wavelength? I'd test it out.

PUR is really just hypothetical. Different clades of zooxanthellae have different photo-responses. Also different corals, even of the same species can have different clades of zooxanthellae, multiple types of zooxanthellae or can even sometimes switch zooxanthellae. Also corals further regulate PUR by producing their own pigments. So, the best you could do really is to measure the photosynthetic response of a given coral, at a given time. The response could change tomorrow... The good news though, is that means they are reasonably adaptable. Dana Riddle did write an article several years ago on the subject and The conclusion was PAR was more important than spectrum, at least for growth. For coloration, spectrum seems to matter a lot more.

 

[dannyp02908]

I've heard of others mentioning photo inhibition from too much light. Wonder if that really is part of the deal with LEDs?