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

[luxdium]

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.

Those would be great questions for @PSXerholic who independently tested the lamp and provided the data for analysis. From what was conveyed, a "HAMILTON CAYMAN SUN MOGUL METAL HALIDE SYSTEM," was utilized with a stock HGS250AG ballast and a new reflector system. But I can confirm that a DE bulb was used.

Will ask him for clarification and update if necessary.

The constructed plot utilized for spectral analysis is derived from data collected after the arc lamp heated the halides and the spectrum stabilized. As you may know, the spectrum shifts after the arc ignites in the discharge tube. So we collected data over the span of 23 hours, 43 minutes, and 21 seconds after the initial firing of the lamp.

I remember Sanjay's plots, but unfortunately, the site they're hosted on no longer loads the spectra when all fields are filled in. Would like to compare our data if it's possible. (III)

However, with respect to that UVB video going around, there are notable discrepancies between it, and a combination of our and others' data. Possible reasons could be the presence of UV-blocking material in the bulbs, or maybe even a different bulb chemistry. The video is not clear on the specifics of their setup.

Going by other's plots of Phoenix 14000K DE bulbs, there is an agreement in that the spectrum sharply tapers off near 350nm (UVA) and that the spectrum does not drastically shift between electronic and M80 ballasts. Thus, it may not be unusual for the UVB to measure so low. (I) (II)


(I)

(II)

(III)

 

[PSXerholic]

That's a typo apparently from a copy and paste from the Halide setup Purchase order.
Here is the Lamp and Ballast used. There is no Phoenix 14 for Mogul as far I know, only DE.

The experts here that did spot that, will do see on the equipment it's what we are talking about on the results.

Hope that helps ;-)

 

[jda]

I appreciate the reply. Double ended bulbs don't work in Mogul fixtures - at a minimum, I would get the equipment right so that other doochers besides me don't bring it up. Also, regular pulse start 250w ballasts significantly under drive the Phoenix 14k and shift the spectrum... significantly. I hate to be a pain, but this is not a good baseline to start a study or test. I can send you m80 ballasts if you want test a 14k Phoenix right, but you have to send them back when you are done - heard Hauquan is going to do a production run of ballasts and ignitors again, but until I see them in the US, these are like gold to me. You can see the difference between pulse start 250w and real m80 with our not-very-good eyes, so I am sure that your more precise instrument will pick up even more.

I don't know anything or respond much to the UVB video. Just does not pass muster to me and I have appreciated other things that Tullio did. I have seen corals collected that are out of the water or shallow enough where UVB could get to them, but who cares since we don't have any light sources to deliver it right now. I believe that 350 to 850nm is useful to coral, but even then, I have to stop MH PAR around 1200-1500 or else corals can burn where they can take well over 2000 PAR with the sun... so something is missing. The lower the level that light can go before they harm coral, the more is missing. Hubris of man thinks that only visible light matters to other things.

I don't expect m80 to get more UVB if that is your goal. Heck, I took a bunch of lights to my alma mater and used an integrated sphere and their $100k spectrometer and we did not hardly find any UVB in the halides, T5s or LEDs that we tested.

I have had the reefs.org site work with some different browsers. I forgot that it is stupidly unreliable. I am glad that some plats are out there with an easy search. I think that somebody should approach r2r about hosting this... would be a good use of their money rather than bribes to be partner members.

Lastly, nobody should be using double ended bulbs without the glass, so I would just not test that anymore. If you are around enough to know of Dr. Joshi's work, then you also likely know of the carnage that people had when trying this on their tanks - you can easily find these with a search on RC.

 

[jda]

Spec on those Phoenix 14k would be about 330-335 watts. Same with Radium 20k and all other true HQI bulbs.

Phoenix Electric Company once did make mogul-based 14k bulbs - the same bulb inside of a glass wrapper with mogul end. The Mogul ones are not used for other lighting in Asia like the DE ones are, so they stopped probably 8-10 years ago. For those who do not know, these are not reefing bulbs, but rather were developed for general type lighting and also happen to work well for reefs. Radium 20k are the same way. Somehow, they do not fall into the purpose of general lighting and are not going to be phased out like street light MH and all of that... at least not in the EU... and I don't know if the Asian market cares at all about mercury. If you found a SE Phoenix 14k, it would certainly be new old stock.

 

[PSXerholic]

I appreciate the reply. Double ended bulbs don't work in Mogul fixtures - at a minimum, I would get the equipment right so that other doochers besides me don't bring it up. Also, regular pulse start 250w ballasts significantly under drive the Phoenix 14k and shift the spectrum... significantly. I hate to be a pain, but this is not a good baseline to start a study or test. I can send you m80 ballasts if you want test a 14k Phoenix right, but you have to send them back when you are done - heard Hauquan is going to do a production run of ballasts and ignitors again, but until I see them in the US, these are like gold to me. You can see the difference between pulse start 250w and real m80 with our not-very-good eyes, so I am sure that your more precise instrument will pick up even more.

I don't know anything or respond much to the UVB video. Just does not pass muster to me and I have appreciated other things that Tullio did. I have seen corals collected that are out of the water or shallow enough where UVB could get to them, but who cares since we don't have any light sources to deliver it right now. I believe that 350 to 850nm is useful to coral, but even then, I have to stop MH PAR around 1200-1500 or else corals can burn where they can take well over 2000 PAR with the sun... so something is missing. The lower the level that light can go before they harm coral, the more is missing. Hubris of man thinks that only visible light matters to other things.

I don't expect m80 to get more UVB if that is your goal. Heck, I took a bunch of lights to my alma mater and used an integrated sphere and their $100k spectrometer and we did not hardly find any UVB in the halides, T5s or LEDs that we tested.

I have had the reefs.org site work with some different browsers. I forgot that it is stupidly unreliable. I am glad that some plats are out there with an easy search. I think that somebody should approach r2r about hosting this... would be a good use of their money rather than bribes to be partner members.

Lastly, nobody should be using double ended bulbs without the glass, so I would just not test that anymore. If you are around enough to know of Dr. Joshi's work, then you also likely know of the carnage that people had when trying this on their tanks - you can easily find these with a search on RC.

Hmmmm, everyone I know threw the M80 away........... and most used electronic ballasts. Hard to get some now.
Not sure what this conversation here is about but I was testing this bulb/setup as I used it very successful in the past with the goal to see "NOW", what spectrum I was providing my corals with in the past.
I had luckily an old and a new bulb to verify if there is a significant spectrum change, which it wasn't.

So I personally would not even interested in testing on a M80 Ballast, but I see your point.
Right now I' buying and reading out all sorts of lights, bulbs, LED fixtures etc. Attic is filling up with equipment now.

 

[oreo54]

and I don't know if the Asian market cares at all about mercury.

I suspect they do care..
but money talks..

https://mercuryconvention.org/sites/default/files/documents/submission_from_organization/JLMA_AnnexAB_positionpaper.pdf

About the Minamata Convention​

The Minamata Convention on Mercury is the most recent global agreement on environment and health, adopted in 2013. It is named after the bay in Japan where, in the mid-20th century, mercury-tainted industrial wastewater poisoned thousands of people, leading to severe health damage that became known as the "Minamata disease."

 

[luxdium]

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!

The spectrometer used for this test was an UPRtek MK350N spectrometer (measurement range: 360-780nm) and results were provided by Eiji Myorin, of 1.023.net. Tests were conducted in Okinawa, Japan while diving.

While an absorption peak for chlorophyll exists in the red band, papers like Wijgerde, T., van Melis, A., Silva, C. I. F., Leal, M. C., Vogels, L., Mutter, C.,et al. (2014). Red light represses the photophysiology of the scleractinian coral Stylophora pistillata demonstrate the repressive effects of energy in that band and show that red light negatively affects the Normalized Difference Vegetation Index (NDVI) (aka. density) of Zooxanthellae. (Wijgerde et al., 2014) has been discussed in several other articles as well.

Regarding 'glitter lines,' they are visual artifacts from the lensing effect of water ripples as they refract the light. Assuming a sinusoidal waveform, the crests focus light to create intense regions, while the troughs spread the light, creating less intense regions. Shallow water corals are apparently not adversely affected by the lensing affects/glitter lines. See: Veal, Cameron James. “Shallow-Water Wave Lensing in Coral Reefs: a Physical and Biological Case Study.” Journals.biologists.com, Journal of Experimental Biology, Dec. 2010, https://journals.biologists.com/jeb...9/Shallow-water-wave-lensing-in-coral-reefs-a.


Edit: In case it's not apparent, the purpose of this thread is to discuss and analyze the spectrum of metal halides, specifically what makes them unique and discuss what may/may not be different with regards to their spectral qualities and potentially with regards to other light sources. This is not a Halide vs LED thread. Sorry for the disappointment.

 

[jda]

Again, if UVB is your thing, I doubt that you will see much more if you used m80. Just be prepared if somebody wants to discredit your work since you did not drive the bulbs to spec and they might have. I do appreciate that you at least listed out what you used and provided clarification. Thanks. I too often see just generic terms like MH or LED or T5 with no details when the best of breed of any can crush a bad implementation of another... not to mention some huge differences with hardware in the same lanes.

I am looking forward to more charts and stuff.

I am still waiting for somebody to explain to me why these corals that are out of the water for long periods of time thrive more than ones grown at even 10m deep, if not for light. I don't expect an answer on this thread since nobody knows... and UVB might be some of it... but I still don't care right now until somebody wants to offer UVB in a light that I can use (that is safe). I have seen these with my own eyes and others in waist deep water and they are amazing.

To everybody else, please sell me your m80s, or offer them for sale instead of throwing them out. They are in huge demand still - 400w Halide power (or 3x Radion xr30 power/coverage) at less wattage.

 

[luxdium]

People are welcome to discredit and come up with their own opinions. That's part of the discussion.

But a 250W bulb would normally be run in a 250W fixture and an undiscerning user would run their bulbs the same manner. Thus, for a real-world test, a 250W-rated bulb would be tested with a 250W ballast. M80 Ballast or not, the spectral plots appear similar. (Red: M80, Blue: Electronic) See below: (I).

If you can share some data on how the spectrum changes (or shifts) with more power with a different ballast, that would be appreciated.

Edit: The graph below was shared by you in 2019.
Source: https://www.reef2reef.com/threads/no-love-for-mh.540931/page-23#post-5673682

One important point to note is the spectra below are not normalized, thus a difference in output arising from the ballasts would result in one plot having a higher amplitude than the other (Y-Axis). By 'shift,' we're discussing a difference in power distribution with regard to the X-Axis.

(I)

 

[oreo54]

Extreme Low Tide At Bangka Island Exposes Corals To Air, And They Survive! | Reef Builders | The Reef and Saltwater Aquarium Blog

Extreme tidal variations happen each month during what is known as a spring tide. This tidal phase happens twice each lunar month and the big swing in tidal heights occurs closes to the new moon.

reefbuilders.com

 

[jda]

Sorry to drone on, but I want you to be educated if you are going to study these. These are not 250w bulbs. They are HQI, which is a different specification. They never were made to be run at 250w. They got named 250w on the American market... because we are idiots. They got named 14k spectrum by some other stupid means. The names stuck. They used to be called PEC HexArc Blue - the "250" only got put onto the bulb when they started to make another bulb for the ANSI m81 ballast which us dumb Americans also called 150w even though it is not 150w. You are running a high end sports car on 83 octane gas... sure you can do it and many probably cannot tell the difference, but the very people who care about what you are testing do know the difference and care. A Ferrari on 83 octane is still fast, but not as fast as it could be.

Most of the people who don't have m80 ballasts on their HQI bulbs at least use the HQI setting on an electronic ballast which is more like 270-280 watts. 250w should not come into play with these bulbs. Calling a HQI bulb 250w is as unfortunate as calling the 20k Radium a 20k bulb... but it is hard to change names.

Most of the difference that you can see between m80 and electronic is likely from the spectrums swapping around 450nm and the higher than proportional spikes from 500-600 range. Again, you can see this with human eyes.

If you really want to study MH, then add some 6500k and 10k to your lists. They are amazing for growth and health... but they can look bad to most current hobbyist's eyes. Again, the temperature rating is very subjective and there are some 10k bulbs with massive output and nice blue spikes that look quite crisp and pop coral nicely that probably are more like 12 or 14k.

 

[oreo54]

Point seemed to be to quantify UV-A,B,C in a sort over average bulb driven averagely..
This was to compare/contrast to the WAY LESS scientific vid that people want to cling to.
It never was meant to be a "be all" type thing.
Yea take 10 different bulbs (could you get 10 different ones) and 10 of each on 10 different ballasts (can you get 10?) and compare.
Like Tuillo did.. oh wait!

I think you are being a bit hard on what the experiment was intending to show.
From my perspective that amount of B pales in comparison to what those tidal flat corals you so greatly cling to get and even that amount isn't considerable.
"C" is just down right dangerous.. IF there was much to speak of ..

Yea some corals can survive desiccation and solar "poisons" for a time. Only to be submerged in a nutrient rich and high sun environment to recover.
Thanks mostly to a heavy slime layer and MAA's..oh and apparently waves..and probably some unknown things.


..and that purple color.. you can see it in bleached corals as well.

The degree of stress
shown by the scleractinian coral colonies was taxon-
speciWc (Fig. 5). While the majority of aVected Acro-
pora colonies had >50% colony mortality, faviids
appeared more resistant, with the majority of aVected
colonies displaying signs of bleaching only.

 

[luxdium]

Sorry to drone on, but I want you to be educated if you are going to study these. These are not 250w bulbs. They are HQI, which is a different specification. They never were made to be run at 250w. They got named 250w on the American market... because we are idiots. They got named 14k spectrum by some other stupid means. The names stuck. They used to be called PEC HexArc Blue - the "250" only got put onto the bulb when they started to make another bulb for the ANSI m81 ballast which us dumb Americans also called 150w even though it is not 150w. You are running a high end sports car on 83 octane gas... sure you can do it and many probably cannot tell the difference, but the very people who care about what you are testing do know the difference and care. A Ferrari on 83 octane is still fast, but not as fast as it could be.

Most of the people who don't have m80 ballasts on their HQI bulbs at least use the HQI setting on an electronic ballast which is more like 270-280 watts. 250w should not come into play with these bulbs. Calling a HQI bulb 250w is as unfortunate as calling the 20k Radium a 20k bulb... but it is hard to change names.

Got to love the semantics of naming, and the inaccuracies of some marketing. I can see how the kelvin rating is most suspect, as some of these bulbs do not give accurate kelvin readings when measured by spectrometers. Not sure how they came to be.

But when we discuss the bulbs, we'll be transparent about which bulb we used and their ratings as advertised by the manufacturers, as that's the data we immediately have on hand. I sense this may be becoming like the "real UV" debate with LEDs. Certain manufacturers call 405nm, "UV," despite UVA ending at 400nm.

Most of the difference that you can see between m80 and electronic is likely from the spectrums swapping around 450nm and the higher than proportional spikes from 500-600 range. Again, you can see this with human eyes.

I'm primarily making this statement that the spectrum does not shift based on the chart you shared, which does not have the 450nm peak swapping around... The amplitude certainly increases with the M80 ballast, but there's no significant shift to the left or the right. You can see this when you overlay the Electronic Ballast's spectrum over the same position as the M80's spectrum. There's little to no X-axis movement. If the data for each were normalized to the same relative intensity, it would be easier to illustrate this.

If you really want to study MH, then add some 6500k and 10k to your lists. They are amazing for growth and health... but they can look bad to most current hobbyist's eyes. Again, the temperature rating is very subjective and there are some 10k bulbs with massive output and nice blue spikes that look quite crisp and pop coral nicely that probably are more like 12 or 14k.

While we can certainly perform similar tests for other CCT lamps, we may not be in a position to test every permutation and combination of bulbs and ballast that exist. There's also something to be said about manufacturing variability. Until you test multiple bulbs and ballasts, a comparative analysis is difficult to pull off. We tested multiple 14000K Phoenix bulbs, and for the most part, our data align with plots you can find on the Phoenix 14000K DE bulbs.

Would like to see Sanjay's data if it's possible to retrieve it.

 

[oreo54]

If I were a coral I'd not want to be exposed.. Sorry couldn't resist.

Mass mortalities of corals following extreme low tides and high solar radiation have been reported in Guam (Yamaguchi, 1975), Eastern Pacific (Glynn, 1976; Eakin, 1996; Zapata et al., 2010; Mejía-Rentería et al., 2019), the Red Sea (Fishelson, 1973; Loya, 1976), Hawaii (Krupp, 1984), Thailand (Brown et al., 1994) the Central Great Barrier Reef (GBR) in Australia (Anthony and Kerswell, 2007), and Indonesia (Ampou et al., 2017). Armstrong et al. (2007) report a cold weather emersion event for Ningaloo in Western Australia, and Hoegh-Guldberg et al. (2005) describe extensive coral bleaching and subsequent partial mortality following a low water level event at Heron Island in the GBR in which corals were exposed to unusually cold conditions and dry winds. Similarly, Fadlallah et al. (1995) notes mass coral mortality in the western Arabian Gulf coincident with winter low tides. In addition to these stressors, low salinities associated with rainfall during low water level events have also been linked to coral mortality Slack-smith (1960), and earlier records summarised in Loya, (1976). Wind stress is also reported to result in bleaching of coral branches facing into the wind during emersion (Leggat et al., 2006). This aspect of coral reef disturbance has received little attention in recent years; however, it is logical that emersion mortality events will inevitably occur on all shallow reef flats, due to the combination of upward coral growth and water level fluctuations at seasonal and interannual time scales.

Daily timing of low tide drives seasonality in intertidal emersion mortality risk

Sea level exerts a fundamental influence on the intertidal zone, where organisms are subject to immersion and emersion at varying timescales and frequencies. While emersed, intertidal organisms are exposed to atmospheric stressors which show marked diurnal and seasonal variability, therefore the...

www.frontiersin.org

 

[oreo54]

Would like to see Sanjay's data if it's possible to retrieve it.

There are bits and pieces with spectrograph readings below 400nm. I've never found the "big table"

Aquarium Frontiers On-Line: Feature

Aquarium Frontiers Feature

Aquarium Frontiers On-Line: Feature

Product Review: Spectral Analysis Of 250w Mogul Base Metal Halide Lamps - Part I

This is a 2-part series covering a number of new lamps that have recently hit the market.

reefs.com

Product Review: Spectral Analysis of 250W Mogul base Metal Halide Lamps – PART II

This article presents the data on the remaining nine 250W mogul base lamps along with the comparison of all the 250W mogul lamps.

reefs.com

Like so...

Just because..

Playing With Poison – Ultraviolet Radiation

This article documents the results of an experiment designed to examine the effects of artificially-produced UVR on symbiotic zooxanthellae. We'll also examine inexpensive ways to test your system and, if necessary, corrective measures one can take.

reefs.com

Whether it is UV-A or UV-B is a moot point. UVR certainly seems responsible for this case of photoinhibition.

Power equivalents--- 1 μW/cm^2 = 10,000 μW/m^2 = 0.01 W/m^2
Lamp A (outlier) 5000 microWatts/cm2 UV-A
50 W/m^2

 

[oreo54]

Huh, never noticed Dana Lamp G

Lamps G = 2-96-watt power compact fluorescent lamps, 9.5″ from sensor, no shield

UV.. NADA.. or barely registering (need raw data)

 

[A. grandis]

The first mistake was made recently when Mike Paletta thought of using halides to specifically target bacterial infections as it would be the "magical remedy" for that. It is not. Even though that isolated experiment showing the relationship between bleaching and Vibrio is valid. I wonder what's going to happen after the first RTN using halides! We always had RTN and STN back in the day under halides, for God's sake!

The second mistake is to think UVR alone is what makes the high percentage of any advantage using halides. As it would be as simple as adding that "UVB" to any LED fixture to "solve the problem"(?) as in that video. Different technologies presenting different qualities and results.

The spectral qualities of metal halides is due to it's amazing ability to offer a relatively strong intensity, and at the same time that real full spectrum (UVR-IR). Again, the distribution and delivery of those photons is what qualifies it's majesty. Simple as that in a very safe package when well planned and applied correctly.

Zooxanthellae will utilize full spectrum as they do in nature. If that is the main reason to use halides, it would be very close to the answer to all questions. There are things we can't still explain, or even know. I believe that full spectrum, and yes, including UVR to IR, but in conjunction with all the other wavelengths is that, again as an orchestra, does the trick. Just like the sunlight.

As Tullio say... if we would try to reproduce the UVR emited by halides it would just melt. It's impossible. That sets me to choose halides already, as for my personal preference for it's results.

Emerson Effect, occuring in the red region of the spectrum, does boost zooxanthellae's photosynthesis because the photosystems are the same in zooxanthllae and green plants. So metal halides do have an advantage in that manner to say the least.

Although I like to see some data with graphics and read some beautiful/ difficult words in a nice post once in a while, I'm still trying to see what is the main purpose of this thread, cause we all know that halides emits UVA and UVB. Is this to debunk that video? Everything in that video wasn't anything new by the way.
The video where Tullio tried to show the differences between halides and LEDs was very spontaneous and wasn't well edited IMO. Very casual and superficial. Some mentioned it gave the impression of an advertisement for his new UV LED. That was a shame cause Tullio actually knows his stuff!
Anyways..

I like Tullio's quote:
"... metal halide is a hard animal to beat!"

Paletta's old halide tank:

 

[A. grandis]

One more thing... "kelvin" is just a number expression that each bulb uses to identify that particular brand and "color". It is not a set universal reference for metal halide bulbs (or any other bulbs) in any way. For example: if you prefer that Phoenix 14K, you will see that as the "real" 14K, while your friend will prefer the Ushio 14K. So he will see the Ushio 14K as the "real" 14K and so on...
The best way to use those numbers is to refer to the specific brand as a specific reference.

 

[luxdium]

There was never a question that halides had or did not have any UV or any other color, but how much? This experiment was actually conducted on December 29-30, 2022, before any such videos came out. There's a dearth of high-resolution data on Metal Halides and spectral analysis. To jump to the conclusion that their success hinges on a particular band is myopic. What we forget is the same elements used to produce the 450nm metal halide peak are also found in LEDs, eg. Indium and Gallium. For LEDs, varying the ratios controls how blue or violet-shifted they are.

Is it really the spectrum or is it the distribution, or is it something else, or is it a combination? Has anyone successfully run a lamp over a system without a reflector?

It is known that Kelvin is approximated from a coordinate system, but goes awry if the light source is not a true blackbody, or as some say, "Planckian."

 

[jda]

Most people want one single thing to blame or put hope in. It was creatine for muscle mass at one time. If you are a dem, then a rep is the source of all problems, or vice versa. The person who cut me off in traffic is why I am so mad today. One person can fix all problems. People who think these things are dumb. This dumb sentiment is just as prevalent in this hobby. People don't have to think as much or learn as much if somebody tells them something like "UVB is the missing link" or "nitrate feeds corals." Then, you get people who think that what they watch on the web, or read about, actually matters when they have never experienced it - parroting and linking does more damage than good. It seems that if you are in a video, then you are an expert nearly beyond reproach - see BRS, UWC with Vibrant, etc. Maybe you have a slick-edited video in your future when you are done? Maybe a talk at MACNA?

Any one thing can make a difference if it is correct. This is not usually the end of the story, but it is a start. If you find even one thing, you can help a lot of folks. If you find more, you can help some who take the time to dig in. I started a health journey in Jan 2022 - I started with just getting to where I could run for 30 minutes. This one thing was not the whole solution, but it helped a lot. Added in diet, some medication, rest, etc. later one, but any one of these things in isolation would have helped a lot.

A particular band might help a lot. Embrace this and you might find something. It might not. Be ready for anything. Jumping to conclusions might be myopic, but finding a single band that could help is not.

I also urge you not to study/present to the simple described in paragraph one. You probably know this.

The old spider reflectors were almost like running a MH bulb without a reflector... but not completely. I ran bulbs without reflectors for days/weeks while I waited for reflectors to come - a super expensive whole-room light that you did not want to directly look at. Horrible experience for the hobbyist, but I don't know that the corals cared at all - light was the same, just not from different angles nor as much of it.

Spectrum and distribution are important. I would also add delivery to your train of thought. The most successful acropora tanks (sorry, nearly all that I care about that I pay attention to) that have LEDs are run at/near 100% on all channels - yes, there are spectrum things here, but also no PWM.

I also appreciate that you all at least acknowledge and have not gone to the insanely ridiculous "photon is a photon" place... like quantums and photons being infinite and somewhat theoretical matters at all except to just convince those simple folks in the first paragraph that you might be smart. Just even admitting that there are differences is a start that most will not make.

If you cannot see that the spectrum does shift with different ballasts, then I will give up. This will be a huge hurdle for you since it does and you can see it just in those overlayed charts. Your peers and people who you are trying to reach know this. At least be prepared.