Have we been wrong in our understanding of PAR this whole time??

[Doctorgori]

My logic is that the sun is full spectrum, and Acropora grow a couple meters deep, or most of them do.If they would like the more blue or almost only blue wavelenghts they would grow much deeper,( some do).I am a simple guy.

I could go dig up the “way back” machine and show that I had a similar argument about 25yrs ago. I could also go back and show I’ve brought up this blue light misinformation thing by starting 2 or 3 threads similar to this but with a totally opposite opinion than the OP

Here is the thing: animals adaptation (fitness) is driven by variables tied to a specific environment
In husbandry you can:
A) duplicate the environment as much as possible (as in using FULL Spectrum/sunlight spectrum)
OR
B) you can try and optimize the environment for the animals particular biology (as in using “blue” spectrums only)

my opinion is you can’t ever go wrong by duplicating a animals natural environment, whereas choice “B” is dependent on how accurate our understanding of a animals biology is…

 

[JoshO]

You have also no evidence that the study was flawless ? Do you ?
Reefbum had halides before with even faster growth how about that ?

Sorry but a study with factual evidence is far better than your opinion which has nothing backing it.
I'm pretty sure his growth now is as good as it ever has been, but just to clear any confusion he used to run 20k radius.

That is not the study we want, we want a study that uses only blue spectrum with the same PAR as a full spectrum lamp and compare them.

Again, see that post, the 2nd study compares different spectrums...blue came out on top

 

[djf91]

I'm not disagreeing for one second than the sun is the best btw. Remember the par numbers associated with the sun at those depths, crazy high compared to what we run. Blue wavelengths will be at their maximum, but it doesn't look blue as the volumes of others are still there in abundance.
If we drop all those values equally until we hit 250 par and then run a much bluer spectrum at 250 par then I'm hypothesizing, based on the studies, the blue will do better.
I can't stress enough I'm not demonizing full spectrum, but the application of par in measuring the energy delivered as a broad statement rather than being spectrum weighted

Trying to follow you here… are there not places on the reef that have exactly this or are you describing an artificial scenario?

 

[Acroguy]

Sorry but a study with factual evidence is far better than your opinion which has nothing backing it.
I'm pretty sure his growth now is as good as it ever has been, but just to clear any confusion he used to run 20k radius.

Again, see that post, the 2nd study compares different spectrums...blue came out on top

Compares but not with the same PAR, as in Only blue spectrum with lets say 500 par vs full spectrum with 500 par.

Iam questioning the study, not saying it was a 100% flawed.

 

[jda]

Does anybody know of a single hobbyist with any kind of experience that says that LED grows all stonies as fast, or faster, than T5s? A few probably. A few about the same. A bunch slower but still grow well enough. Some die back. This is similar to Dr. Johsi's observations. Ask ReefBum if he wants some of his corals back after switching - I have not asked him, but he lost some beauties. While any one of these is just an anecdote, the mass group of them is a pattern, or better.

With this group of evidence in mind when looking at that study, it is good to read it and understand but also not reasonable to question if it truly was just those two corals.

When you see a long term pattern and then a study that says different, there are two conclusions that can be made... first is that the study has more nuance to understand on why it does not follow the long term pattern, or two, they are just better than everybody else.

 

[oreo54]

Does anybody know of a single hobbyist with any kind of experience that says that LED grows all stonies as fast, or faster, than T5s? A few probably. A few about the same. A bunch slower but still grow well enough. Some die back. This is similar to Dr. Johsi's observations. Ask ReefBum if he wants some of his corals back after switching - I have not asked him, but he lost some beauties. While any one of these is just an anecdote, the mass group of them is a pattern, or better.

With this group of evidence in mind when looking at that study, it is good to read it and understand but also not reasonable to question if it truly was just those two corals.

When you see a long term pattern and then a study that says different, there are two conclusions that can be made... first is that the study has more nuance to understand on why it does not follow the long term pattern, or two, they are just better than everybody else.

Has the same been observed going...backwards?
Say from led to mh?

Even I have no doubt that corals adapt to whatever spectrum they are given but are slow on the uptake..

Switching spectrums regardless of which one considers " better" is apparently problematic.

Second... How about a list of which did better, worse, died, grew faster ect .

 

[ISpeakForTheSeas]

Compares but not with the same PAR, as in Only blue spectrum with lets say 500 par vs full spectrum with 500 par.

Iam questioning the study, not saying it was a 100% flawed.

The study below tested Acropora variabilis and Porites lutea harvested from 2-6 m deep at maintained 6 m deep; they compared dark (no light), full-spectrum (the control), and blue light settings at 200 μmol and 400 μmol (they tested full-spectrum at 800 μmol as well, but 400 μmol was the highest they could get the blue); they used a metal halide light with polycarbonate filters to control what spectrum the corals were being exposed to - the corals grew (calcified) fastest under the blue light, but there was more photosynthesis under the full-spectrum (white) light:

"The light to dark calcification ratios of A. variabilis under 400 μmol photons m−2 s−1 of control and blue light were 8.4 and 10.5, respectively; while lower ratios were observed in P. lutea (3.4 and 4.5). In both cases, calcification under blue light exceeds even these of the control"

Light Enhanced Calcification in Hermatypic Corals: New Insights from Light Spectral Responses

Light enhanced calcification (LEC) is a well-documented phenomenon in reef-building corals. The main mechanism proposed for LEC is that photosynthetic CO2 uptake by the algal symbionts elevates the pH and thus enhances calcification. We evaluated the role of light and of photosynthesis on...

www.frontiersin.org

So, under controlled PAR with metal halides, these shallow water corals grew faster under blue light than white, but but photosynthesis decreased drastically under blue light when compared to white.

To contrast with that, though, another study (using three different species of Acropora - A. tenuis, A. muricata, and A. intermedia at 100 μmol and 200 μmol [low numbers, I know] with LED's) compared different spectrums (the first link below) and found that the inclusion of some red light drastically increased the growth rate (the second link below; the green/yellow spectrum made a little bit of difference, but they didn't add much of it in with any of the three spectrums used; it may have made a bigger difference at higher intensities):

https://www.researchgate.net/figure/Light-spectra-composition-of-LEDs-used-in-the-current-study-A-PBR-400nm-purple-430nm_fig1_367478086

https://www.researchgate.net/figure/Specific-growth-rate-of-three-Acroporid-corals-under-different-light-spectra-Values-are_fig6_367478086

The actual study:

https://www.researchgate.net/publication/367478086_Effects_of_light_intensity_and_spectral_composition_on_the_growth_and_physiological_adaptation_of_Acroporid_corals

Another contrasting study - Stylophora pistillata from shallow (3 m) and deep (40 m) waters; the shallow specimens showed the highest photosynthesis rates under full-spectrum lighting, but the deepwater specimens showed the highest photosynthesis rates under blue lighting (sadly, they didn't measure growth rates, and the study only took place between March and April, so it was rather short, and results may have changed if the study had been longer).

The spectral quality of light is a key driver of photosynthesis and photoadaptation in Stylophora pistillata colonies from different depths in the Red Sea

SUMMARYDepth zonation on coral reefs is largely driven by the amount of downwelling, photosynthetically active radiation (PAR) that is absorbed by the symbiotic algae (zooxanthellae) of corals. The minimum light requirements of zooxanthellae are related to both the total intensity of downwelling...

journals.biologists.com

So, does blue light grow Acropora or other SPS faster than full-spectrum (white) light? It depends on the coral (both species and individual specimen), the location and depth/temperature the coral is from, what light the corals are photo-acclimated to (a shallow water coral growing under blue light in a hobbyist tank for 5 years is likely going to be acclimated to blue light despite its origins), year-round weather conditions (storms and such play a big role in determining what light is reaching the water), the clade of zooxanthellae they're using, etc.

Does the kind of light used (metal halide vs t5 vs LED, etc.) make a difference, or is it all in the spectrum, intensity, and photoperiod? I don't think we'll be able to answer this unless someone is able to make LED's with the exact same spectrum as those other types of lighting, but I'd guess any differences would be minimal.

So, lots of different things go into the growth, and again, fast growth doesn't necessarily equate to excellent health/coloration (it might, but it also might not). Does each coral species have it's own optimal spectrum for growth/health/color? Probably, but I doubt it would perfectly match a different species own optimal spectrum, so I don't know that it would much matter in our tanks - instead, we'd need to find the optimal spectrum for a broad range of corals, which may not be optimal for any particular coral we keep:

"Zooxanthellate corals display contrasting photoacclimation responses, coral cover, colony morphologies and genetic richness along depth gradients33,49,50,51,52,53,54, which collectively suggest that coral species occupy different light niches."

Photosynthetic usable energy explains vertical patterns of biodiversity in zooxanthellate corals - Scientific Reports

The biodiversity in coral reef ecosystems is distributed heterogeneously across spatial and temporal scales, being commonly influenced by biogeographic factors, habitat area and disturbance frequency. A potential association between gradients of usable energy and biodiversity patterns has...

www.nature.com

Personally, I'd expect to see similar (not the same, but similar) growth rates from a lot of corals under both blue and full-spectrum lights; some will likely do better under one than the other, but determining which is a lot of effort.

For that reason, like I've said before, at this point in time (barring a major, undeniable scientific breakthrough with our knowledge of corals and light), I would personally only suggest running the windex blue tanks if you really want to see the coral fluorescence pop (as mentioned by others, though, the colors may be best in the long run if you run different spectrums than just blue throughout the day). Like many others have mentioned in various forms by this point, I'd personally run a full-spectrum (white) light that leans somewhat more toward the blue side of things. Is that the "best" spectrum? Maybe, maybe not, but it seems like a good, safe place to start from.

 

[BeanAnimal]

May as well get this out there too…

Evolution vs adaption

Our established shallow clear water reefs are a new thing with the average age being somewhere in the 5,000 to 10,000 years old range (built as the last ice age ended). These are a good bit different than ice age reefs that come and go every ~100,000 years for the last 3 million years, and vastly different than the reefs from 3-12 million years ago, and those are vastly different than the reefs of 12 million to 500 million years old. All of which (3 - 500) appear to have been dark water (deep or highly turbid) reefs with no "clear water" shallow reefs.

Acropora, albeit ancient is thought to have only become a dominant reef builder in the last 3 million years with the shallow reefs that have come and gone with the cyclical 100,000 year ice ages that only started ~3 million years ago. Has it changed from its dark turbid water ancestor or just adapted in the "modern" era without much (or any) change and just grows faster when given more light? It is "reef dominant" because it grows fast and as the water changed as much as 125 meters per 100,000 year cycle over the last 3 million years it survived where other sesile inverts perished in deep darker water or dried up on land. Is the 50,000 year half cycle enough to evolve the acroprora or is it just hardy and in a constant state of adaption with not enough time to evolve?

What is the "ideal" environment for acropora, seeing that it adapts to light or dark where other corals don't so easily (as evidenced by the last 3 million years of reefs)? (rhetorical, we are guessing). We are on a warming phase for the next 40 thousand years, so none of us will know what happens when we turn the corner again to usher in the next ice age.

Just more for the reef lighting philosophers to add to the definitive "this is the way it works" answers.

So with ALL of the variables (light, flow, chemistry) - trial and error, some pretty cool and some pretty bad studies... we know very little and most of what we do is trial and error and follow the leader. We learn from our local failures and successes.

 

[djf91]

The study below tested Acropora variabilis and Porites lutea harvested from 2-6 m deep at maintained 6 m deep; they compared dark (no light), full-spectrum (the control), and blue light settings at 200 μmol and 400 μmol (they tested full-spectrum at 800 μmol as well, but 400 μmol was the highest they could get the blue); they used a metal halide light with polycarbonate filters to control what spectrum the corals were being exposed to - the corals grew (calcified) fastest under the blue light, but there was more photosynthesis under the full-spectrum (white) light:

"The light to dark calcification ratios of A. variabilis under 400 μmol photons m−2 s−1 of control and blue light were 8.4 and 10.5, respectively; while lower ratios were observed in P. lutea (3.4 and 4.5). In both cases, calcification under blue light exceeds even these of the control"

Light Enhanced Calcification in Hermatypic Corals: New Insights from Light Spectral Responses

Light enhanced calcification (LEC) is a well-documented phenomenon in reef-building corals. The main mechanism proposed for LEC is that photosynthetic CO2 uptake by the algal symbionts elevates the pH and thus enhances calcification. We evaluated the role of light and of photosynthesis on...

www.frontiersin.org

So, under controlled PAR with metal halides, these shallow water corals grew faster under blue light than white, but but photosynthesis decreased drastically under blue light when compared to white.

To contrast with that, though, another study (using three different species of Acropora - A. tenuis, A. muricata, and A. intermedia at 100 μmol and 200 μmol [low numbers, I know] with LED's) compared different spectrums (the first link below) and found that the inclusion of some red light drastically increased the growth rate (the second link below; the green/yellow spectrum made a little bit of difference, but they didn't add much of it in with any of the three spectrums used; it may have made a bigger difference at higher intensities):

https://www.researchgate.net/figure/Light-spectra-composition-of-LEDs-used-in-the-current-study-A-PBR-400nm-purple-430nm_fig1_367478086

https://www.researchgate.net/figure/Specific-growth-rate-of-three-Acroporid-corals-under-different-light-spectra-Values-are_fig6_367478086

The actual study:

https://www.researchgate.net/publication/367478086_Effects_of_light_intensity_and_spectral_composition_on_the_growth_and_physiological_adaptation_of_Acroporid_corals

Another contrasting study - Stylophora pistillata from shallow (3 m) and deep (40 m) waters; the shallow specimens showed the highest photosynthesis rates under full-spectrum lighting, but the deepwater specimens showed the highest photosynthesis rates under blue lighting (sadly, they didn't measure growth rates, and the study only took place between March and April, so it was rather short, and results may have changed if the study had been longer).

The spectral quality of light is a key driver of photosynthesis and photoadaptation in Stylophora pistillata colonies from different depths in the Red Sea

SUMMARYDepth zonation on coral reefs is largely driven by the amount of downwelling, photosynthetically active radiation (PAR) that is absorbed by the symbiotic algae (zooxanthellae) of corals. The minimum light requirements of zooxanthellae are related to both the total intensity of downwelling...

journals.biologists.com

So, does blue light grow Acropora or other SPS faster than full-spectrum (white) light? It depends on the coral (both species and individual specimen), the location and depth/temperature the coral is from, what light the corals are photo-acclimated to (a shallow water coral growing under blue light in a hobbyist tank for 5 years is likely going to be acclimated to blue light despite its origins), year-round weather conditions (storms and such play a big role in determining what light is reaching the water), the clade of zooxanthellae they're using, etc.

Does the kind of light used (metal halide vs t5 vs LED, etc.) make a difference, or is it all in the spectrum, intensity, and photoperiod? I don't think we'll be able to answer this unless someone is able to make LED's with the exact same spectrum as those other types of lighting, but I'd guess any differences would be minimal.

So, lots of different things go into the growth, and again, fast growth doesn't necessarily equate to excellent health/coloration (it might, but it also might not). Does each coral species have it's own optimal spectrum for growth/health/color? Probably, but I doubt it would perfectly match a different species own optimal spectrum, so I don't know that it would much matter in our tanks - instead, we'd need to find the optimal spectrum for a broad range of corals, which may not be optimal for any particular coral we keep:

"Zooxanthellate corals display contrasting photoacclimation responses, coral cover, colony morphologies and genetic richness along depth gradients33,49,50,51,52,53,54, which collectively suggest that coral species occupy different light niches."

Photosynthetic usable energy explains vertical patterns of biodiversity in zooxanthellate corals - Scientific Reports

The biodiversity in coral reef ecosystems is distributed heterogeneously across spatial and temporal scales, being commonly influenced by biogeographic factors, habitat area and disturbance frequency. A potential association between gradients of usable energy and biodiversity patterns has...

www.nature.com

Personally, I'd expect to see similar (not the same, but similar) growth rates from a lot of corals under both blue and full-spectrum lights; some will likely do better under one than the other, but determining which is a lot of effort.

For that reason, like I've said before, at this point in time (barring a major, undeniable scientific breakthrough with our knowledge of corals and light), I would personally only suggest running the windex blue tanks if you really want to see the coral fluorescence pop (as mentioned by others, though, the colors may be best in the long run if you run different spectrums than just blue throughout the day). Like many others have mentioned in various forms by this point, I'd personally run a full-spectrum (white) light that leans somewhat more toward the blue side of things. Is that the "best" spectrum? Maybe, maybe not, but it seems like a good, safe place to start from.

Very well said. Thank you for those studies.

Could full spectrum light benefit the reef ecosystem and coral holobiont as a whole and thus be better for coral health. We know that coral health/success is very much intertwined with the microbial communities of the whole reef.

 

[oreo54]

For "fun" for those that think "nature knows best"..

For instance, a 2016 marine heat wave killed 30 percent of coral in the Great Barrier Reef, a study published online April 18 in Nature reports.

Ahhh.. "nature"...

She always trying to kill you..

And more for fun during this intermission.



PLEASE note the laminar (boundary) layer is all encompassing, just shrinking or expanding due to fluid dynamics.

One more:

Marine Actinomycetes Associated with Stony Corals: A Potential Hotspot for Specialized Metabolites

Microbial secondary metabolites are an important source of antibiotics currently available for combating drug-resistant pathogens. These important secondary metabolites are produced by various microorganisms, including Actinobacteria. Actinobacteria have a colossal genome with a wide array of...

www.mdpi.com

Last, the hint came from the vid..

Endozoicomonas - Wikipedia

en.wikipedia.org

Role in the environment​

The presence of Endozoicomonas in the marine ecosystem is associated with the overall coral health, serving as a marker of the general well-being of corals and the organisms that inhabit in coral reefs, as well as reducing the presence of pathogenic bacteria that may try to infect the coral.[21] Other functions associated to Endozoicomonas relate to amino acid and vitamin synthesis, in the production of metabolites while contributing with nitrogen and sulfur cycles,[7] and to transfer organic molecules which avidly helps in the nutrition of its host, yet their exact function and the way in which their presence affects all these organisms is still yet to be determined.[18][22]

During coral bleaching, Endozoicomonas populations remain present in the water in low amounts, indicating a certain level of resilience, and the absence of a healthy coral community leads to changes in the population amounts of these bacteria.[23] Other environmental factors and stressors such as temperature changes, acidification of the ocean, and anthropogenic activities have a direct impact as well in the abundance of these microorganisms in their habitat.

In contrast to their reputation as beneficial symbionts, their genome reveals potential mechanisms for bacterial adaptation and some pathogenic species are being discovered and described to be affecting fish larvae cultures, causing epitheliocystis and further leading to mass mortality

 

[djf91]

Seasonal Variations in the Culturable Mycobiome of Acropora loripes along a Depth Gradient

Coral associated fungi are widespread, highly diverse and are part and parcel of the coral holobiont. To study how environmental conditions prevailing near the coral-host may affect fungal diversity, the culturable (isolated on potato dextrose agar) mycobiome ...

www.ncbi.nlm.nih.gov

The abundance of fungi increased with increasing water depth, where corals sampled at 25 m yielded up to 70% more fungal colony forming units (CFUs) than those isolated at 6 m.

Fragments were sampled from both apparently healthy coral colonies as well as those exhibiting observable lesions.

Diversity was also higher in lesioned coral samples, when compared to apparently healthy colonies.

 

[JoshO]

The study below tested Acropora variabilis and Porites lutea harvested from 2-6 m deep at maintained 6 m deep; they compared dark (no light), full-spectrum (the control), and blue light settings at 200 μmol and 400 μmol (they tested full-spectrum at 800 μmol as well, but 400 μmol was the highest they could get the blue); they used a metal halide light with polycarbonate filters to control what spectrum the corals were being exposed to - the corals grew (calcified) fastest under the blue light, but there was more photosynthesis under the full-spectrum (white) light:

"The light to dark calcification ratios of A. variabilis under 400 μmol photons m−2 s−1 of control and blue light were 8.4 and 10.5, respectively; while lower ratios were observed in P. lutea (3.4 and 4.5). In both cases, calcification under blue light exceeds even these of the control"

Light Enhanced Calcification in Hermatypic Corals: New Insights from Light Spectral Responses

Light enhanced calcification (LEC) is a well-documented phenomenon in reef-building corals. The main mechanism proposed for LEC is that photosynthetic CO2 uptake by the algal symbionts elevates the pH and thus enhances calcification. We evaluated the role of light and of photosynthesis on...

www.frontiersin.org

So, under controlled PAR with metal halides, these shallow water corals grew faster under blue light than white, but but photosynthesis decreased drastically under blue light when compared to white.

To contrast with that, though, another study (using three different species of Acropora - A. tenuis, A. muricata, and A. intermedia at 100 μmol and 200 μmol [low numbers, I know] with LED's) compared different spectrums (the first link below) and found that the inclusion of some red light drastically increased the growth rate (the second link below; the green/yellow spectrum made a little bit of difference, but they didn't add much of it in with any of the three spectrums used; it may have made a bigger difference at higher intensities):

https://www.researchgate.net/figure/Light-spectra-composition-of-LEDs-used-in-the-current-study-A-PBR-400nm-purple-430nm_fig1_367478086

https://www.researchgate.net/figure/Specific-growth-rate-of-three-Acroporid-corals-under-different-light-spectra-Values-are_fig6_367478086

The actual study:

https://www.researchgate.net/publication/367478086_Effects_of_light_intensity_and_spectral_composition_on_the_growth_and_physiological_adaptation_of_Acroporid_corals

Another contrasting study - Stylophora pistillata from shallow (3 m) and deep (40 m) waters; the shallow specimens showed the highest photosynthesis rates under full-spectrum lighting, but the deepwater specimens showed the highest photosynthesis rates under blue lighting (sadly, they didn't measure growth rates, and the study only took place between March and April, so it was rather short, and results may have changed if the study had been longer).

The spectral quality of light is a key driver of photosynthesis and photoadaptation in Stylophora pistillata colonies from different depths in the Red Sea

SUMMARYDepth zonation on coral reefs is largely driven by the amount of downwelling, photosynthetically active radiation (PAR) that is absorbed by the symbiotic algae (zooxanthellae) of corals. The minimum light requirements of zooxanthellae are related to both the total intensity of downwelling...

journals.biologists.com

So, does blue light grow Acropora or other SPS faster than full-spectrum (white) light? It depends on the coral (both species and individual specimen), the location and depth/temperature the coral is from, what light the corals are photo-acclimated to (a shallow water coral growing under blue light in a hobbyist tank for 5 years is likely going to be acclimated to blue light despite its origins), year-round weather conditions (storms and such play a big role in determining what light is reaching the water), the clade of zooxanthellae they're using, etc.

Does the kind of light used (metal halide vs t5 vs LED, etc.) make a difference, or is it all in the spectrum, intensity, and photoperiod? I don't think we'll be able to answer this unless someone is able to make LED's with the exact same spectrum as those other types of lighting, but I'd guess any differences would be minimal.

So, lots of different things go into the growth, and again, fast growth doesn't necessarily equate to excellent health/coloration (it might, but it also might not). Does each coral species have it's own optimal spectrum for growth/health/color? Probably, but I doubt it would perfectly match a different species own optimal spectrum, so I don't know that it would much matter in our tanks - instead, we'd need to find the optimal spectrum for a broad range of corals, which may not be optimal for any particular coral we keep:

"Zooxanthellate corals display contrasting photoacclimation responses, coral cover, colony morphologies and genetic richness along depth gradients33,49,50,51,52,53,54, which collectively suggest that coral species occupy different light niches."

Photosynthetic usable energy explains vertical patterns of biodiversity in zooxanthellate corals - Scientific Reports

The biodiversity in coral reef ecosystems is distributed heterogeneously across spatial and temporal scales, being commonly influenced by biogeographic factors, habitat area and disturbance frequency. A potential association between gradients of usable energy and biodiversity patterns has...

www.nature.com

Personally, I'd expect to see similar (not the same, but similar) growth rates from a lot of corals under both blue and full-spectrum lights; some will likely do better under one than the other, but determining which is a lot of effort.

For that reason, like I've said before, at this point in time (barring a major, undeniable scientific breakthrough with our knowledge of corals and light), I would personally only suggest running the windex blue tanks if you really want to see the coral fluorescence pop (as mentioned by others, though, the colors may be best in the long run if you run different spectrums than just blue throughout the day). Like many others have mentioned in various forms by this point, I'd personally run a full-spectrum (white) light that leans somewhat more toward the blue side of things. Is that the "best" spectrum? Maybe, maybe not, but it seems like a good, safe place to start from.

Incredible reply. I really appreciate the time and effort that has gone into that. This is precisely why I started this discussion, to really dig into the knowledge of the users on here!
I'm definitely in the camp of running a combination of the 2. I have approximately 5 hours of full spectrum, with the remaining 7 sat around the 16k mark. Both temperatures I run show different colours in the corals, which I really enjoy. Is it beneficial for the health? I couldn't possibly answer that without physically taking various measurements.
I do like to keep my blue and violet channels at 100% (I also run red at 25%) outside of the ramp up and down, then add in the various other channels to suit the appearance.
It would be amazing to find a study that measures the benefits of each wavelength to better understand the volume by which it should be delivered, but again that would be coral specific, so very hard to find a middle ground for all

 

[areefer01]

Well why don't we just put this to rest unless someone wants to set up a real world experiment. Same coral, same weight, same size test tank, centered in the same location, plumbed together, same fish, same rock, substrate, or none (the same), with the only difference being the light used (mh, led). Oh, PAR number has to be the same. Exactly the same. The only difference would be spectrum and with the LED used that could, of course, be set differently. So once set it can't be changed.

Otherwise we are sort of just going nowhere in this thread as there is no common ground.

 

[Acroguy]

For "fun" for those that think "nature knows best"..

Ahhh.. "nature"...

She always trying to kill you..

And more for fun during this intermission.



PLEASE note the laminar (boundary) layer is all encompassing, just shrinking or expanding due to fluid dynamics.

One more:

Marine Actinomycetes Associated with Stony Corals: A Potential Hotspot for Specialized Metabolites

Microbial secondary metabolites are an important source of antibiotics currently available for combating drug-resistant pathogens. These important secondary metabolites are produced by various microorganisms, including Actinobacteria. Actinobacteria have a colossal genome with a wide array of...

www.mdpi.com

Last, the hint came from the vid..

Endozoicomonas - Wikipedia

en.wikipedia.org

You cant influence nature, just like when a volcano erupts. But the sun is constant.

 

[oreo54]

You cant influence nature, just like when a volcano erupts. But the sun is constant.

As in how?
Color temp and intensity change all the time.
Caustic networks " beam" par fluctuations continuously.

Not much really constant actually.
Even in space you got solar storms,/ wind "fluctuating" the suns output.

Probably more philosophical I suppose.

Sun: Facts - NASA Science

From our vantage point on Earth, the Sun may appear like an unchanging source of light and heat in the sky. But the Sun is a dynamic star, constantly changing and sending energy out into space. The science of studying the Sun and its influence throughout the solar system is called heliophysics...

science.nasa.gov

From our vantage point on Earth, the Sun may appear like an unchanging source of light and heat in the sky. But the Sun is a dynamic star, constantly changing and sending energy out into space.

 

[jda]

Well why don't we just put this to rest unless someone wants to set up a real world experiment. Same coral, same weight, same size test tank, centered in the same location, plumbed together, same fish, same rock, substrate, or none (the same), with the only difference being the light used (mh, led). Oh, PAR number has to be the same. Exactly the same. The only difference would be spectrum and with the LED used that could, of course, be set differently. So once set it can't be changed.

Otherwise we are sort of just going nowhere in this thread as there is no common ground.

This started to happen with a store in Cali. Got a little way into the experiment and all of a sudden a "partnership" was announced with a big LED manufacturer. Ran into them at a show and they said that could not turn down the money, free gear and larger margin to be a "partner store." They had die back on the LED side, no change to the MH side. When they went all LED, the die back of the same species happened on the other side too. They still had a nice tank, but with a subset of the acropora that they had before.

Do you know that I have Gen 4 Radions over one of my frag tanks? Same system. It is not the same. There is common ground when you have used them all and understand the nuance and things - you might like or hate one type of light more than the other, but they are not the same. My Colorado Sunbursts move out from under the Radions an over the to the side with the 14k Phoenix - this could flow which I think is pretty even and I am no fool, but it happens. The acropora frags do not grow as fast under the Radions. The polyps and mushrooms don't seem to care at all. I have lots of ORA German Blue Digi (not an easy coral) grow OK in these tanks, but have a different growth pattern - the Radion side have green body and the 14k Phoenix side have white body. I think that I have photos of all of this in my tank thread.

For some of the posters on this thread, they are not guessing, they have experienced what they have posted about.

 

[Acroguy]

As in how?
Color temp and intensity change all the time.
Caustic networks " beam" par fluctuations continuously.

Not much really constant actually.
Even in space you got solar storms,/ wind "fluctuating" the suns output.

Probably more philosophical I suppose.

Sun: Facts - NASA Science

From our vantage point on Earth, the Sun may appear like an unchanging source of light and heat in the sky. But the Sun is a dynamic star, constantly changing and sending energy out into space. The science of studying the Sun and its influence throughout the solar system is called heliophysics...

science.nasa.gov

Ok, put it differently, The sunshine is constant the whole year around, it rises and sets each day. It is the same every year. You posted that the water heated up and corals died. That happens sometimes, that is not even worth comparing to sunshine or spectrum because it is a “ one time event “ .The sun isnt changing from year to year. Its pretty much the same and will be for a long time.

 

[BeanAnimal]

FWIW ORA Blue Digi under Mitras
Sorry - way too lazy to white balance.

 

[BeanAnimal]

There - a bit better

 

[Acroguy]

There - a bit better

Looks like a milka stylo