Reef nutrition

Dana's Talk - Red, Blue and UV Light

bprestwo

bprestwo

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I enjoyed the talk. Thanks again BAR board for putting it on.

Dana's research on red light shows it damages at least some corals. I'm looking forward to his next project on the subject. Practical applications seem simple, don't use red light.

Dana's comments about UV and blue light were also informative. He stated unambigiously that...
  • UV is not necessary
  • Corals use blue light more effeciently than UV
  • Blue light doesn't damage the corals like UV
    He would avoid UV if at all possible

His inlcussion, at the end of the meeting, of 3 UV LEDs in is his ideal LED fixture seemed a bit contradictory. I'm going with his earlier comments on UV and blue light.

Dana's comments about zooxanthelle having no affect on color were a bit baffling to me. His comment that zooxanthelle only occur thinly and near the coralites seems contradict pretty much everything that is driving the SPS market these days. On the other hand, the ULN guys are targetting NSW levels of PO4 and NO3 (fertilizer) and calling it ultra-low.

Do you think Dana meant that when fertilizer levels are at NSW zooxanthelle have almost no affect on color because they only occur thinly and coralites?
 
One thing that I forgot to ask a question about, re: red light, was that if in his testing did he use exclusively red light which could mean that the corals simply can't use it as opposed to it being damaging.
 
bprestwo said:
Dana's research on red light shows it damages at least some corals. I'm looking forward to his next project on the subject. Practical applications seem simple, don't use red light. ....
Click to expand...

Well, I think it is important to be precise in this case : He said a "LOT" of red light damages corals.
And I had seen similar research when I looked around deciding what LEDs to use for my system.
I still have not seen any research that says a "normal amount" has any effect.
Normal being defined as : The amount of red versus other spectra being no higher percentage than normal sunlight.

So if you have a little bit of red added for human aesthetics, not the same thing.
 
bprestwo said:
Dana's comments about UV and blue light were also informative. He stated unambigiously that...
  • UV is not necessary
  • Corals use blue light more effeciently than UV
  • Blue light doesn't damage the corals like UV
    He would avoid UV if at all possible

His inlcussion, at the end of the meeting, of 3 UV LEDs in is his ideal LED fixture seemed a bit contradictory. I'm going with his earlier comments on UV and blue light.
Click to expand...

I didn't get that either. Why include UV if they are useless/harmful?

He seemed open to email contact so perhaps ONE of us could gather the questions we were too shy to ask :) and contact him.
 
It could be that the UV will create a fluorescence however being as we can't see UV all we'll see is fluorescence and unlike with "blue" where you see a mixture of the fluorescence + blue.

Or it could be that UV will trigger different fluorescence proteins and give a bit of a different levels, akin to an actinic fluorescence vs a blue fluorescence.
 
Keep in mind that UV is a very generic color. It just means wavelengths shorter than 400 nm. I find the statement to general and the cutoff to arbitrary. DNA damage does not happen till you hit UVC wavelengths. UVB can cause sunburns, and we actually need small amounts to produce vitamine D. No, we aren't corals, but terrestrial plants play by similar rules.
 
My impression was that he thought UV-A was good, but was a bit reluctant to push it, since the deeper UVs are
bad, and there are risks dealing with any UV.
 
rygh said:
My impression was that he thought UV-A was good, but was a bit reluctant to push it, since the deeper UVs are
bad, and there are risks dealing with any UV.
Click to expand...

That was my take away as well. Some small amount of UV-A produces nice fluorescence. Too much UV-A is bad and UV-B/C are always bad.
 
bondolo said:
rygh said:
My impression was that he thought UV-A was good, but was a bit reluctant to push it, since the deeper UVs are
bad, and there are risks dealing with any UV.
Click to expand...

That was my take away as well. Some small amount of UV-A produces nice fluorescence. Too much UV-A is bad and UV-B/C are always bad.
Click to expand...

I got the same message from him- some UV is ok but not too much. What was real clear to me was he was anti-red, I believe calling it a 'fad', and thought that having some green, around 500 nm (I think) was good. He also liked the ratio of 1:1 for whites/ blues. That's too white for me, but everyone has their own color taste.

If I were to design my LED fixture incorporating Dana's advice (except I prefer more blues than whites) I would have something like:
55% blue LEDs
30% white
5-10% green
5% or less UV
 
Keep in mind that "blue" is a rather generic term.

I have been following some good RC threads on coloring, and combing all that,
If I was doing it over, I might build a cluster of:
1 x Neutral white (Luxeon, not Cree)
1 x Royal Blue (450 nm)
2 x Violet (395nm - 430nm)
1 x Cyan (505 nm, greenish blue)

That may seem a bit odd, but the Violet looks rather dim to humans, but has good PAR values,
and fluoresces well. So the theory is you get lots of blue wavelengths, but a less blue looking tank.
Also, the violet can fool the eye into seeing red a bit. And it is not really UV, so no risks.
And the nuetral white, instead of cool whine, gives better CRI and when combined with violet
eliminates the need for red.
The cyan fills that hole to the right of the blue that is so common in LEDs.
 
Aloha BAR members-
Thank you again for the enjoyable visit and chance to present at your club. I had been told that your group was advanced, and my impression certainly confirms that. The questions were all thoughtful.

Re: Some of the questions above.
Yes, I can see where some of my statements seem contradictory. I should have been more specific when answering questions. First, UV is a broad term. Metal halides in general produce a lot of ultraviolet radiation (some of it harmful to corals and humans), and the double-ended lamps in particular make some UV-C. In a broad sense, I suggest to stay away from UV since our discussions didn't usually state which light source is used.
When we discuss specifics (LEDs, for instance) the answer changes. Including UV LEDs is something I would recommend if you're looking to build or buy a LED system. UV LEDs (at least those I have tested) produce very little UV-A. Since most of us can't see into the UV spectrum, UV LEDs also produce violet light so we know they haven't burned out. This UV/violet light has a couple of advantages. As far as I know, violet blue light will induce coloration and UV isn't necessary. However, there are a number of coral colors that absorb light into the UV/violet portion of the spectrum. Hence, including a few UV/violet LEDs won't make the color, but it will sure make the coral color fluoresce very nicely (I think *pop* is the term many hobbyists use).
In a nutshell, UV isn't necessary in order for the coral to produce the fluorescent protein, but UV will make the fluorescence more apparent than if you're using just blue LEDs, especially those making most of their light around 450nm. Fluorescent protein production and display of those fluorescent proteins are two different issues.

Red light. I nearly pulled that part of the presentation since it is so controversial (and sometimes confusing). A lot of red light is bad for zooxanthellae. That much is unequivocable. When I mentioned red lights being a 'fad', I meant that some vendors are hyping there products based on terrestrial plant research. Personally, I think enough red light is produced by wide spectrum LEDs (meaning white ones) and red supplementation isn't needed. Almost invariably, those making LED fixtures don't do much research, other than Googling some algae absorption spectra (this is readily apparent when they show the absorptions of chlorophylls 'a' and 'b'. Corals do not contain chlorophyll 'b'! But they do contain chlorophylls 'a' and 'c2'). In essence, you are doing the product testing for the vendor. If the results are negative, they'll change their product and you're left with maybe a few dead corals. As I mentioned, I'll begin research on the effects of red light when I get back to Hawaii. I had a chlorophyll meter built for me, but it arrived too late for me to get any meaningful answers before traveling to San Francisco.

Green light. Those LEDs producing green light peaking around 500-525 should be OK, since the photopigment perdinin absorbs this light thus boosting photosynthesis.

I'll check back in a few days.
Dana
 
Hi Dana, I've been reading up on your publications and unfortunately missed your presentation due to obligations that required me to be out of town. Thanks for taking the time to follow up i the BAR forum!

1. Does photoinhibition only occur with UVR, or does it also occur with high-energy blue light (assuming the intensity is strong enough)?

2. You have described many fluorescent pigments, and overall their excitation spectra covers a wide range of wavelengths. Is the output intensity of typical white LEDs on some of the popular LED fixtures today capable of inducing excitation in most fluorescent pigments?

3. Which photopigments do you recommend targeting to optimize photosynthesis? In other words, is there an "ideal" light spectrum for enhancing zooxanthellae photosynthesis?
 
Great clarification!

Amusingly, the whole red controversy is a lot like the old bare-bottom versus sand bed.

If you dive on a big reef:
A) There is very little red left in the light.
B) There is no sand bed.

However, to my non-reefer friends, and even to what I find aesthetically pleasing:
A) Royal Blue + Cool white looks weird without a bit of red.
B) A send bed looks nice and is expected as "normal".

For fun: Enclosed is quick graph on spectrum absorption, to add even more confusion.
Chlorophyll-f-spectrum.jpg
 
And to add to this, the chlorophyll c* regions absorption spectrum here's a paper on it here
www.plantphysiol.org/content/91/2/727.full.pdf

But if you just want pretty pictures, click image below, the "C" box is the c2 that Dana mentions before, as you can see almost a complete lack of red absorption and a ton of blue.


Attached files /attachments/sites/default/files/chlor_0.jpg
 
Unless Mark's picture is a log scale, there's significantly more red absorption in chlorophyll a.

That said, I think people want red over their tanks not so much to stimulate growth but to bring out red colors more :D
 
Given Dana's observations regarding red light, is it possible to suggest that the proportion of chlorophyll c2 is higher than chlorophyll a in zooxanthellae?

If that is the case, then does the amount of chlorophyll a pose a bottleneck in photosynthetic activity? As I understand it the higher energy wavelengths require additional processing and become "red" light before they enter one of the photosystems. Absorbed photons from shorter wavelengths lose energy along the way down to 680nm before being utilized in Photosystem II by chlorophyll a .
funnel.gif

http://plantphys.info/plant_physiology/lightrxn.shtml
 
sfsuphysics said:
Unless Mark's picture is a log scale, there's significantly more red absorption in chlorophyll a.
Click to expand...
Are you looking at the chlorophyll F curve? If so, ignore that. I think that is only in certain fairly rare cyanobacteria.
The area under the A curve is larger in the blue.

sfsuphysics said:
That said, I think people want red over their tanks not so much to stimulate growth but to bring out red colors more :D
Click to expand...
Yes!
Well, other than those of us that also use it for their alga scrubber. Lots of red works great there!
 
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