What's in a Metal Halide spectrum? What's the secret spectral sauce?

[luxdium]

What's in a Metal Halide spectrum? What's the secret spectral sauce? How much UV does it really have?​

The answer greatly depends on the ratios of the halide salts used, the gasses, and whether the outer fused silica glass has been doped to absorb the UV from the mercury vapor discharge.

With some guidance from @Dana Riddle and independently verified extended range spectrum measurements by @PSXerholic , together, we've quantified the spectral qualities of a DE 250W Phoenix 14000K Hex Arc Blue Metal Halide bulb installed in a Hamilton Cayman Mogul Metal Halide System.

Although the bulb has a narrow spectral peak in the blue band (~453nm), it has representation in the other bands to be a full-spectrum light. When all spectral bands are considered, UV makes ~4.510% (~5%) of the total spectral output. Of the UV, UV-A is the most dominant band, making about 95.520% (96%) of the total UV output. Contrary to expectations, the UV-B representation was low, making about 0.234% (0%) of the total spectral output and about 3.934% (4%) of the total UV output.

In light of these findings, while UV is present in Metal Halides like this 14000K Phoenix, it is minor compared to the other spectrum bands. To further analyze the composition of the UV band, the spectrometer's measurement window was adjusted to integrate from 230-399nm with the same integration time as the full-spectrum measurement (2ms). To account for any potential shifts due to the cover glass, separate measurements were taken with and without the cover glass installed in the fixture.

Our findings are attached below.

[1] Full 14000K Lamp Spectral Composition Analysis (230-850nm)
[2] UV Spectral Composition Analysis With Glass Cover (230-399nm)
[3] UV Spectral Composition Analysis Without Glass Cover (230-399nm)

 

[Bpb]

This is interesting. I’ll preface by saying I don’t have a dog in this fight. But these results seem to run directly counter to the claims recently made in the whole uvb video making the rounds. Thoughts? Not necessarily on the merits of uv, but on why others seem to be claiming such disparate readings?

 

[luxdium]

Several things.

The bulbs play a large role, especially if UV-opaque dopant was deposited in the outer fused silica glass.
Some lamps have this added to improve the safety of their use. This may explain why the Phoenix 14000K has so little UVB.

That UVB video going around also has several nuances. They use a spectrometer that can introduce errors via autofluorescence in the fiber optic cable and an extended integration time which can "oversmoothen/overexpose" the spectrum, making it broader than it actually is. For example, it shows a Radion G6 Pro having a spectral peak at 425nm. Even per Ecotech's own published spectra, those lights do not peak at 425nm unless there were some major adjustments done to the sliders or the fiber optic end was placed close to a violet LED. Going by the PAR measurements mentioned in the video, they likely maxed the light out (ran it at 100% across all channels). Since Radions are some of the more well-tested lights, this spectrum is anomalous to what is accepted for those lights.

Thus, it's more likely the below spectrum was produced by an extended integration time, sensor placement, or a combination of them. It's not clear how they set their test.

 

[oreo54]

Several things.

"snip"

Out of curiosity do you have the power numbers of the available UV?
Like microwatts/cm2

The general order of microbial resistance (from least to most) and corresponding UV doses for extensive (> 99.9%) inactivation are: vegetative bacteria and the protozoan parasites Cryptosporidium parvum and Giardia lamblia at low doses (1-10 mJ/cm2) and enteric viruses and bacterial spores at high doses (30-150 mJ/cm2). ...However, dissolved organic matter, such as natural organic matter, certain inorganic contaminants, such as iron, sulfites and nitrites, and suspended matter (particulates or turbidity) will absorb UV radiation or shield microbes from UV radiation, resulting in lower delivered UV doses and reduced microbial disinfection.

Any proof UV-A has anything but ..err..cosmetic effects associated with it?
Or to waste resources producing MAA's though I did read some corals produce them even in the absence of UV as a stimulus.
Oh ignoring photosynthesis since any blue/violet is capable.

 

[Bpb]

Several things.

The bulbs play a large role, especially if UV-opaque dopant was deposited in the outer fused silica glass.
Some lamps have this added to improve the safety of their use. This may explain why the Phoenix 14000K has so little UVB.

That UVB video going around also has several nuances. They use a spectrometer that can introduce errors via autofluorescence in the fiber optic cable and an extended integration time which can "oversmoothen/overexpose" the spectrum, making it broader than it actually is. For example, it shows a Radion G6 Pro having a spectral peak at 425nm. Even per Ecotech's own published spectra, those lights do not peak at 425nm unless there were some major adjustments done to the sliders or the fiber optic end was placed close to a violet LED. Going by the PAR measurements mentioned in the video, they likely maxed the light out (ran it at 100% across all channels). Since Radions are some of the more well-tested lights, this spectrum is anomalous to what is accepted for those lights.

Thus, it's more likely the below spectrum was produced by an extended integration time, sensor placement, or a combination of them. It's not clear how they set their test.

Makes sense. I found their “experiment” to be lacking in just about every accepted control protocol even grade school level science classes would accept, beginning with “we found this meter online, check it out”. IIRC it was an Amazon purchase. Not that it is inherently junk because of the warehouse it came from, but just because the entire thing seemed very haphazard.

What seems to be lacking is evidence people can actually digest which tells us the metabolic benefits of adding high energy UV wavelengths to our tanks, and is it worth the constant uvb exposure to your and your families eyes and skin just to achieve trace anecdotal improvements in coral health at best? I realize I’m kind of steering the conversation but I think it’s relevant. If not, disregard

 

[luxdium]

Out of curiosity do you have the power numbers of the available UV?
Like microwatts/cm2

Yes, however, that number depends on the measurement distance and the measurement location in the light field. Since spectra are ratios, quantifying the bands as percentages makes it easier to explain how much of a certain color is present.

For reference, these samples were taken approximately 14 inches from the light source, at the center. Summing the energies of the light within the UV band comes to ~4732.842704 mW/m^2/nm which amounts to ~0.04882% or ~5% of the total light output. Of the UV, UV-A (315-399nm) is the most dominant, comprising about 4.51% of the total output.

Any proof UV-A has anything but ..err..cosmetic effects associated with it?
Or to waste resources producing MAA's though I did read some corals produce them even in the absence of UV as a stimulus.
Oh ignoring photosynthesis since any blue/violet is capable.

The data are out there, but most studies on UVR demonstrate the negative aspects, for example, decreased calcium uptake and bleaching due to photo-oxidation. However, some positive aspects could be facilitating UV vision, as certain reef fish like damsels (Pomacentridae) can see UV. There is another study on how UV prevents Vibrio shiloi-induced bleaching, however, no other bleaching events apart from those documented in the Mediterranean have been attributed to V. shiloi. Of the few benefits, this one may be worth exploring. Though given Vibrio are motile via flagella, it is plausible that prevention via the use of a UV-C sterilizer may also be effective.

 

[oreo54]

Yes, however, that number depends on the measurement distance and the measurement location in the light field. Since spectra are ratios, quantifying the bands as percentages makes it easier to explain how much of a certain color is present.

For reference, these samples were taken approximately 14 inches from the light source, at the center. Summing the energies of the light within the UV band comes to ~4732.842704 mW/m^2/nm which amounts to ~0.04882% or ~5% of the total light output. Of the UV, UV-A (315-399nm) is the most dominant, comprising about 4.51% of the total output.



The data are out there, but most studies on UVR demonstrate the negative aspects, for example, decreased calcium uptake and bleaching due to photo-oxidation. However, some positive aspects could be facilitating UV vision, as certain reef fish like damsels (Pomacentridae) can see UV. There is another study on how UV prevents Vibrio shiloi-induced bleaching, however, no other bleaching events apart from those documented in the Mediterranean have been attributed to V. shiloi. Of the few benefits, this one may be worth exploring. Though given Vibrio are motile via flagella, it is plausible that prevention via the use of a UV-C sterilizer may also be effective.

Yes the data is out there for the "real world" ... but reef aquariums are not the real world..
Anyways 2 interesting papers..

Other than these relatively few studies that show the positive
effects of UVR in coral reef systems, all other studies suggest
that the effects of UVR are negative.

 

[luxdium]

Yes the data is out there for the "real world" ... but reef aquariums are not the real world..
Anyways 2 interesting papers..

That's another thing. Most studies are on phytoplankton. Even the paper that describes how PUR is calculated is also based on research on marine phytoplankton photosynthesis.

 

[A. grandis]

Thanks for the data, @luxdium! Well done!

In regards to UVR, I believe it works amazingly like an orchestra when it is within the full spectrum from metal halides. The whole spectrum is what should be considered, and not just the UV wavelengths. As you noted, every metal halide bulb will offer the full spectrum with the representation in all bands. I also think the IR is important for the balance of the spectrum, just like in nature.
Also, the metal halide spectrum comes in a golden package where we find glitter lines, intensity and distribution, when applied correctly.

Could you please give us your point of view on the potential benefits of Emerson Effect in photosynthesis by the symbionts with the analysis of the metal halide spectrum in comparison to most LEDs?

 

[oreo54]

There is another study on how UV prevents Vibrio shiloi-induced bleaching, however, no other bleaching events apart from those documented in the Mediterranean have been attributed to V. shiloi. Of the few benefits, this one may be worth exploring. Though given Vibrio are motile via flagella, it is plausible that prevention via the use of a UV-C sterilizer may also be effective.

Antibiotics work. Also apparently non- motile in the presence of corals(????)

V. shiloi is not flagellated and individual cells are smaller, approximately 1.0 x 2.0 micrometers. [2] V. shiloi does not have bioluminescence properties, does not produce spores, and when cultured on agar in laboratory has slightly serrated edges and observing swarming consistent with presence of flagella. [2] V. shiloi yields positive catalase and oxidase testing, reduces nitrate to nitite, is a facultative aerobe, and is capable of acidic fermentation. [2] V. shiloi obtains energy from a number of carbohydrate sources including glucose, sucrose, dextrose and glycogen. [2]

The scleractinian coral Oculina patagonica undergoes bleaching (loss of its endosymbiotic zooxanthellae) every summer in the eastern Mediterranean Sea when seawater temperatures rise.......
V. shiloi is only capable of exerting pathogenic, coral bleaching effects on Oculina patagonica zooxanthellae between the temperatures of 20-32°C [2] but reaches a maximum efficacy around 29-30°C. [5] However, the V. shiloi life cycle is sensitive to the antibiotics penicillin, ampicillin, tetracycline, oxytetracycline, streptomycin and kanamycin as well as 2,4-diamino- 6,7-diisopropylpteridine. [2]

Vibrio shiloi - microbewiki

microbewiki.kenyon.edu

Just keep your tank cooler ..
Sorry,couldn't resist.

Several of the virulence factors, such as adhesin, toxin, and superoxide dismutase, are produced only at the elevated summer seawater temperatures.

The Vibrio shiloi/Oculina patagonica model system of coral bleaching - PubMed

The scleractinian coral Oculina patagonica undergoes bleaching (loss of its endosymbiotic zooxanthellae) every summer in the eastern Mediterranean Sea when seawater temperatures rise. The causative agent of the disease is Vibrio shiloi. The pathogen adheres to a beta-galactoside-containing...

pubmed.ncbi.nlm.nih.gov

Just for interest.

 

[oreo54]

~4732.842704 mW/m^2/nm
Total uv-a+b+c
= 473.28 microW/ cm^2/ nm @ 14"

Trying to put perspective on lamp exposure levels.
0.546% uv-c
473.28 *.00546 = 2.58 microW/cm^2/nm
3.934% uv-b
473.28 *.03934 = 18.62 microW/cm^2/nm
95.52% uv-a
473.28 * .9552. = 452.08 microW/cm^2/nm

The details for the L2S case are as
follows:
‐ Our UV tube is 8W with 28 μW/cm2,
‐ The UV band used 253.7 nm (UV C),
‐ The distance to target is 30 cm max.
As UV intensity is inversely proportional to
the square of the distance, and our
distance is 0.3 in
comparison to 1 m, the formula to apply is
the following*:
UV dose μWs/cm2 = UV intensity μW/cm2 × exposure time (seconds) / (0.3)2
Applying our figures, we get the following
formula:
UV dose μWs/cm2 = 28 × exposure time (seconds) / 0.09
An exposure for 10 mins, or 10 x 60 = 600 seconds, results in:
UV dose μWs/cm2 = 28 × 600 / 0.09 = 186,666 μW∙s/cm2, which is far above the required dose.

36000 sec (10hr day) x 2.58 = 92880
12" down with the light at 14" (14" already accounted for since that is the distance it was measured at )
92880/ 12^2 ( inverse sq rule ( iffy under water))

645 microW* sec/cm^2/nm uv-c exposure.

12" under water,light at 14" 10hr day,uv-c
Glass covered light %'s

Dosages for a 90% kill of most bacteria and viruses range from 2,000 to 8,000 μW∙s/cm2.

Soo uv-looks pretty ineffective as a sterilizer for the sand bed.
.
670,320/144 = 4,655 microW*sec/ cm^2
Uv-b same conditions above.
.
Doesn't account for species tolerance variations or a host of other stuff probably..

Using the 8000 figure and 10hrs of light theoretically the uv-c exposure should be pretty fatal (for everything) at
92880/ x^2 = 8000
0-3.4" under water.


Please check the math.
A reminder:

UVC radiation from the sun does not reach the earth’s surface because it is blocked by the ozone layer in the atmosphere.

Thus, the only way that humans can be exposed to UVC radiation is from an artificial source like a lamp or laser.

In other words uv-c is un- natural in the ocean... Afaict.

Last thing..It may be worthwhile to do the same analysis with t5's.

 

[luxdium]

Thanks for the data, @luxdium! Well done!

In regards to UVR, I believe it works amazingly like an orchestra when it is within the full spectrum from metal halides. The whole spectrum is what should be considered, and not just the UV wavelengths. As you noted, every metal halide bulb will offer the full spectrum with the representation in all bands. I also think the IR is important for the balance of the spectrum, just like in nature.
Also, the metal halide spectrum comes in a golden package where we find glitter lines, intensity and distribution, when applied correctly.

One of the misleading things about spectral plots is narrow bands as being 'incomplete.' They have representation in the other colors, just that a single color is more dominant than the others.

Regarding red, and other longer wavelength colors, very few find their way where corals grow. For example, here's a spectrometer placed near wild colonies. At 2.8 meters (~9 feet), Far-red (700nm < ʎ <781nm, the last line), attenuates to virtually undetectable amounts. The further you go up the spectrum, the more strongly the water absorbs the spectrum. IR, in general, can be regarded as heat.

The Emerson Effect has been studied on terrestrial plants. However, corals having evolved in an environment where red and far light attenuate, may not have evolved the same shade avoidance responses as plants. Additionally, red light is known to regulate endosymbiont density.

 

[luxdium]

~4732.842704 mW/m^2/nm
Total uv-a+b+c
= 473.28 microW/ cm^2/ nm @ 14"

Trying to put perspective on lamp exposure levels.
0.546% uv-c
473.28 *.00546 = 2.58 microW/cm^2/nm
3.934% uv-b
473.28 *.03934 = 18.62 microW/cm^2/nm
95.52% uv-a
473.28 * .9552. = 452.08 microW/cm^2/nm




36000 sec (10hr day) x 2.58 = 92880
12" down with the light at 14" (14" already accounted for since that is the distance it was measured at )
92880/ 12^2 ( inverse sq rule ( iffy under water))

645 microW* sec/cm^2/nm uv-c exposure.

12" under water,light at 14" 10hr day,uv-c
Glass covered light %'s


Soo uv-looks pretty ineffective as a sterilizer for the sand bed.
.
670,320/144 = 4,655 microW*sec/ cm^2
Uv-b same conditions above.
.
Doesn't account for species tolerance variations or a host of other stuff probably..

Using the 8000 figure and 10hrs of light theoretically the uv-c exposure should be pretty fatal (for everything) at
92880/ x^2 = 8000
0-3.4" under water.


Please check the math.
A reminder:


In other words uv-c is un- natural in the ocean... Afaict.

Last thing..It may be worthwhile to do the same analysis with t5's.

Analysis for T5's is coming up.

 

[piranhaman00]

Link to uvb video?

 

[luxdium]

Link to uvb video?

It's on YouTube. Search for " "Shedding LIGHT" on REEF Aquarium Lighting. "

 

[A. grandis]

One of the misleading things about spectral plots is narrow bands as being 'incomplete.' They have representation in the other colors, just that a single color is more dominant than the others.

Regarding red, and other longer wavelength colors, very few find their way where corals grow. For example, here's a spectrometer placed near wild colonies. At 2.8 meters (~9 feet), Far-red (700nm < ʎ <781nm, the last line), attenuates to virtually undetectable amounts. The further you go up the spectrum, the more strongly the water absorbs the spectrum. IR, in general, can be regarded as heat.

The Emerson Effect has been studied on terrestrial plants. However, corals having evolved in an environment where red and far light attenuate, may not have evolved the same shade avoidance responses as plants. Additionally, red light is known to regulate endosymbiont density.

Thanks very much for the reply!!

Please let me know what are the corals in the picture. P. verrucosa? What is the Acropora sp.? Nice!
What is the instrument's specs and brand/model, please?
Where was the picture taken?

If the red light is known to regulate endosymbiont's density, it is a very important part of the full spectrum, right? Please bring up some papers for that observation. I love it!

1) Could you please expose the relationship between the red wavelengths and glitter lines over shallow water corals?

2) Doesn't the glitter lines also have a strong relationship for the projection of the red wavelengths (and all other wavelengths) for the corals to regulate their endosymbiont's density (and to perform other functions)?

3) Any other wavelengths are used to regulate the density of endosymbionts?

4) What would be other important aspect of the red wavelengths for the coral's metabolism when applied within the full spectrum from sun light or metal halides?

Thanks!

 

[A. grandis]

It's on YouTube. Search for " "Shedding LIGHT" on REEF Aquarium Lighting. "

@piranhaman00

 

[oreo54]

High ppfd red light only (660nm) is used experimentally to bleach corals.. There is that..

A reminder:

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/323017562
Living off the Sun: chlorophylls, bacteriochlorophylls and rhodopsins
Article in Photosynthetica · February 2018

 

[jda]

My apologies if I missed this, but how did you test a double ended bulb in a Cayman Sun Mogul setup? Also, what ballast did you use? If you did not use a ANSI m80, can you please do this again? The spectrum changes with more power, not just the output.

Anybody who has seen Dr. Joshi's spectral plots from a few decades ago knows that UVB is not really even worth discussing - rounding error. These are still hosted and can be seen.

 

[A. grandis]

How did I missed those 2 huge observations!?!?
Something is wrong here!
I'm going further than that... would be great to see pictures of that experimental setup.
Also, the op's avatar is a LED company's logo.
What is the purpose of this thread, really?

Luxdium

Luxdium designs and builds the ultimate upgrade path for your lights. With a simple cluster swap, LUX Engine takes your aging AquaIllumination fixtures to new levels of spectrum and light output.

www.luxdium.com