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

A. grandis

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It does because some hobbyist are not able to have a normal discussion and insist their way is the best and/or only way. Anything else and the fingers go in the air while singing LA LA LA at the top of their lungs.
Thanks.
 

oreo54

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It does because some hobbyist are not able to have a normal discussion and insist their way is the best and/or only way. Anything else and the fingers go in the air while singing LA LA LA at the top of their lungs.
Now that is funny, how this can be taken many ways....
 
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luxdium

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There's a bit of noise with respect to the signal, but to recap:

MH tested for analysis:
Phoenix 14000K 250W DE
-Chosen because of popularity and historically proven results.​
-*DE base fixture, NOT Mogul (was a typo in the invoice that got copied over to the graph description)​
This should not affect the results of the experiment, but important to clarify.​
-Electronic ballast used. It's the same one supplied by the manufacturer. What most hobbyists will use.​

Spectrum:
-Have UV, but not as much as one may expect. (~4.883%)​
-UVA is represented more than any other form of UV. (~4.510%/4.883% = ~92.361%)​
-Representation in UVB and UVC is negligible. (~0.234% + ~0.139% = ~0.373%)​
-Have R, FR, and IR (~20.843%)​
-Blue band makes up a majority of the spectrum with a peak around 453nm (~40.209%)​
-Shades of green-blue to yellow make up ~19.752% of the spectrum.​
Note that these ratios apply to the Phoenix 14000K 250W DE bulbs in this experiment. Other bulbs may differ due to different compositions and the presence of UV-blocking materials.​
Light distribution technique:
Possible Discussion Question:
-MH lamps have reflectors. Does this influence the results? Any trials w/o the reflectors?​

Natural vs Artificial:
Can MH spectral success be attributed to emulating nature?
>Define nature.
-Certain corals in the wild get exposed to air or are in shallow water. Possibly more exposure to other bands like UV and red. Bands like red, far-red, and IR attenuate rapidly at depth and UVB and other shortwave and longwave light are virtually non-existent at depths most corals for the hobby are collected. Edge cases will always exist.​
-Phoenix 14000K DE bulb does not appear to emulate natural spectra.​
-It's possible for modern lighting technologies to replicate some of the natural spectra.​
Possible Discussion Question:​
Is emulating nature in a closed system a sound idea if other confounding variables are not fully understood?​
 

oreo54

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Some UV is lost by the natural absorbance of the reflector material.
2 common materials being aluminum and silver, though I believe it is a sputtered silver alloy for most?
Anyways chart is for first surface mirrors..
Do not know the % that is direct or reflected light.

silverabs.JPG
 
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Hurricane Aquatics

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There's a bit of noise with respect to the signal, but to recap:

MH tested for analysis:
Phoenix 14000K 250W DE
-Chosen because of popularity and historically proven results.​
-*DE base fixture, NOT Mogul (was a typo in the invoice that got copied over to the graph description)​
This should not affect the results of the experiment, but important to clarify.​
-Electronic ballast used. It's the same one supplied by the manufacturer. What most hobbyists will use.​

Spectrum:
-Have UV, but not as much as one may expect. (~4.883%)​
-UVA is represented more than any other form of UV. (~4.510%/4.883% = ~92.361%)​
-Representation in UVB and UVC is negligible. (~0.234% + ~0.139% = ~0.373%)​
-Have R, FR, and IR (~20.843%)​
-Blue band makes up a majority of the spectrum with a peak around 453nm (~40.209%)​
-Shades of green-blue to yellow make up ~19.752% of the spectrum.​
Note that these ratios apply to the Phoenix 14000K 250W DE bulbs in this experiment. Other bulbs may differ due to different compositions and the presence of UV-blocking materials.​
Light distribution technique:
Possible Discussion Question:
-MH lamps have reflectors. Does this influence the results? Any trials w/o the reflectors?​

Natural vs Artificial:
Can MH spectral success be attributed to emulating nature?
>Define nature.
-Certain corals in the wild get exposed to air or are in shallow water. Possibly more exposure to other bands like UV and red. Bands like red, far-red, and IR attenuate rapidly at depth and UVB and other shortwave and longwave light are virtually non-existent at depths most corals for the hobby are collected. Edge cases will always exist.​
-Phoenix 14000K DE bulb does not appear to emulate natural spectra.​
-It's possible for modern lighting technologies to replicate some of the natural spectra.​
Possible Discussion Question:​
Is emulating nature in a closed system a sound idea if other confounding variables are not fully understood?​

If this is true "Have R, FR, and IR (~20.843%)" I see that as being the HUGE difference between MH and LED.

To me, that tells about everything we need to know as LED doesn't produce that.
 
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luxdium

luxdium

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If this is true "Have R, FR, and IR (~20.843%)" I see that as being the HUGE difference between MH and LED.

To me, that tells about everything we need to know as LED doesn't produce that.
LEDs do produce R, FR, and IR. It depends on whether the requisite emitters are added. For IR, some can be a byproduct of the heat generated from UV LEDs. However, IR and FR rapidly attenuate as they pass through water.
 

oreo54

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If this is true "Have R, FR, and IR (~20.843%)" I see that as being the HUGE difference between MH and LED.

To me, that tells about everything we need to know as LED doesn't produce that.

The " reds" need to have a function for that to count.
Like saying the sun produces radio waves that make it to earth. Mh's don't.
That is a huge difference from the sun.

l6tYD.jpg


It only matters if it matters ..
 

Hurricane Aquatics

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The " reds" need to have a function for that to count.
Like saying the sun produces radio waves that make it to earth. Mh's don't.
That is a huge difference from the sun.

l6tYD.jpg


It only matters if it matters ..

We're all speculating at best. @Dana Riddle any input on this thread?
 

Eric R.

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@luxdium @PSXerholic

Thank you for doing the work and writing up your results. This is the sort of information that I find interesting to read. Unfortunately the signal-to-noise ratio ended up getting a little high in the thread.

Has anyone tried reaching out to Sanjay directly to see if he has the data you are looking for?
 

Eric R.

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Also, @luxdium, you should check out the reef beef discord. I think you might enjoy the conversations that happen on there. I'd like to think there is a lower signal-to-noise ratio, but I might simply be biased.
 

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