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

[JoshO]

Can't change the laws of physics, if you absorp the photon like you say you absorp the energy. Any and all of that energy that is not used has to go somewhere. The simplest way to get rid of it is releasing it as heat. Since corals are very sensitive to heat, that isn't the best solution. The mechanism they therefore use is converting it back in a photon and releasing it. Now the question is, is increasing this fluorescence by adding more blue spectrum really helping the coral?
Like Lasse said the actual photo reactive center found in chlorophyll contains a primairy pigment p680 or p700 (p=pigment and the 680 and 700 stand for the nm of light of the photon that is directly converted in an electron by this pigment, so red light). That electron is what is passed on for the chemical reaction. Directly attached to this photo reactive center is a secondairy pigment that absorps light in the 400nm to 500nm range (so blue light) to create an electron that is passed on, so transported to the primairy pigment. Like any and all kind of transport there is some kind of loss/inefficiency. All other pigments found in corals that use light at different wavelentgths are attached to this photo reactive system and therefore the electrons created also need to be transported along a longer pathway probably incuring greater losses than even that of the blue absorption pigment.
Red light of the right wavelength is therefore most efficient and in theory all corals need if you provide the right amount, it would make them really ugly. All flesh would be transparent so you would see nothing but white skeleton except for a minimum amount of brown zoõxanthellae. Don't think they would be very healthy though under such unnatural conditions. The major problem with red spectrum light is that there really isn't any much room for fluorescence if you get to much of it, so the only option left may be trying to survive the heatstress. Which corals are bad at.

I understand the concept of what's being implied by the way in which the light is used and converterted.
Going off your last paragraph, we are talking about coral health and providing them with the optimum conditions for colouration and growth. You've said there that red would likely result in ugly corals, and also cause them to die of heat stress?

This is a study of stylophora pistillata under a number of different lighting scenarios at 2 intensities. You can see that by week 6 that only 3 groups have zero mortality. Those are either all blue or blue/red with low intensity. I fully understand your point that it maybe needs to be regulated so accurately to provide the absolute correct amount, but with regards to what we do in this hobby it clearly serves no benefit. There is a reason the blue light is so successful, and I may be misunderstanding the direct link to energy and it's usefulness in photosynthesis. But if we revisit my original point of all par isn't equal, the arguement that certain spectrums are more important than others (whether it be red or blue) then I think both perspectives back this

 

[Reefering1]

Shim shimmer!! who got the keys to my Beamer! lol

Ohh myyy..

 

[MabuyaQ]

The screenshot response was not rhetorical, I was trying to understand the context of the commenters statement. It bore no relevance to the statement I was making in that simply measuring par without understanding spectrum is a bad way of doing things as it's very inaccurate. I'm not disputing unused light energy will create heat, but absolutely a different subject to the one I'm bringing to the table.

I fully agree with PAR not being the end all solution to coral light, but I wasn't the one ranking blue light higher than yellow light as well. In reality thers is a coral species out there that has the right pigments to be able to fullfill al its energy needs and thrive with 200 PAR of that yellow light that would barely hold on to live with 200 PAR of that blue light.
So if you pick a spectrum you also pick a certain set of corals that will thrive, the rest will just barely survive. So the best general solution may be a wide balanced spectrum to cover most of the bases.

 

[Lasse]

Here is my spectra at max run

And here is my aquarium at the same time

Case closed

Sincerely Lasse

 

[Kfactor]

hear comes the washed out blue tanks lol

 

[Reefering1]

I just don't see the point fiddling with measuring spectrum, par, pur and trying to think you understand what is "best" for corals- when you can simply include it all and distribute it well by turning the halides on. Plug it in and worry about something else. It even looks better when you can see what's in your tank

 

[JoshO]

Read my links again - this is not true

Sincerely Lasse

Blue light does result in more energy, that is stated further up on the wiki page you're referencing. Shorter, higher frequency of waves is more energy.
Whilst I appreciate that the energy may be utilised differently once absorbed it doesn't detract from the fact that if we light our tanks with a fixed rate of par with blue v red light we are going to see vastly different results. I may be wrong in my interpretation of how the energy is used, but it's been proven by numerous studies that blue light is the most beneficial to coral health.
Like I say, I may be slightly misinterpreting the way in which "energy" plays a role, but ultimately my original point that par cannot simply be interpreted as an "energy" reading by which we can base all spectrums on a reef tank is absolutely valid. Blue light evidently has far more importance and is absorbed more by chlorophyll a and b than red light

 

[JoshO]

I fully agree with PAR not being the end all solution to coral light, but I wasn't the one ranking blue light higher than yellow light as well. In reality thers is a coral species out there that has the right pigments to be able to fullfill al its energy needs and thrive with 200 PAR of that yellow light that would barely hold on to live with 200 PAR of that blue light.
So if you pick a spectrum you also pick a certain set of corals that will thrive, the rest will just barely survive. So the best general solution may be a wide balanced spectrum to cover most of the bases.

This absolutely isn't the case. If you were to harness yellow light specifically using an LED and eliminate all other spectrums then no coral would thrive under it. If you were using a "yellow" metal halide it would include the full spectrum, so the blue end of the spectrum would still exist, it just wouldn't be visible to your eye.
This is where we fall down. There is no disputing the wavelengths that are absorbed for photosynthesis. The issue we have is when most hobbyists are now running LEDs and are reducing the output of blue to achieve a certain colour temperature. It doesn't provide the same energy a metal halide of the same temperature would as the higher frequencies simply are not there in the correct volume

 

[JoshO]

Here is my spectra at max run

And here is my aquarium at the same time

Case closed

Sincerely Lasse

It's great to see you're running such a good LED fixture...I run the same but if we look at the spectral mix displayed at the top, and the supposed colour temperature...it's very blue. I appreciate the picture doesn't show that, but my whole point is that we need to focus on having a high proportion of blue light as that provides the most energy. The number of red LEDs in each puck is totally outnumbered by the various blue and violets, which again shows the importance of blue!
My original point with this thread is that a new hobbyist may run the blues reduced to achieve a 6500k aesthetic let's say with extra fixtures to increase the par to match yours. You're likely going to have more success due to the high levels of blue

 

[Koleswrath]

reducing the output of blue to

I find that folks who want a more natural looking reef tank are actually turning up the whites, not turning down the blues. Also, as you stated above the number of blue and violet diodes on almost every LED fixture far outnumber the reds/greens and even whites resulting in a fairly tough to fatally screw up lighting system.

 

[JoshO]

I find that folks who want a more natural looking reef tank are actually turning up the whites, not turning down the blues. Also, as you stated above the number of blue and violet diodes on almost every LED fixture far outnumber the reds/greens and even whites resulting in a fairly tough to fatally screw up lighting system.

You'll find a lot dialling back blue if they're trying to hit a par goal but also have that natural daylight look. It's nearly impossible to have both. With my Mitras, if I want a maximum of 250 par then I can only run all channels at roughly 60% to achieve roughly 12k

 

[JoshO]

I fully agree with PAR not being the end all solution to coral light, but I wasn't the one ranking blue light higher than yellow light as well. In reality thers is a coral species out there that has the right pigments to be able to fullfill al its energy needs and thrive with 200 PAR of that yellow light that would barely hold on to live with 200 PAR of that blue light.
So if you pick a spectrum you also pick a certain set of corals that will thrive, the rest will just barely survive. So the best general solution may be a wide balanced spectrum to cover most of the bases.

This is the spectrum of a 6500k iwasaki. You can see significant peaks in the blue light range despite the yellow appearance of the overall spectrum. If you had 250 par of 570nm LEDs you'd find little to no corals that could survive

 

[KrisReef]

I know, it's a discussion . Your point here is exactly what I'm implying needs to be done. We need to measure our par by only measuring the blue end of the spectrum (and possibly a very small amount of red, but that's debatable with how important blue is. I'm currently reading a study on red repression). Then if we leave the blues alone and add in the whites for our own visual pleasure we'll have a much more effective lighting set up.
For clarification this relates to LEDs more than other light sources. A 6500k metal halide will have all the blue necessary most likely, it just has a lot of the other wavelengths too. The par this gives out will be significantly high than day a 20000k MH I'd assume

Photosynthesis occurs under many wavelegths (that are absorbed and used for growth), not just the blue portion of the spectrum adds to energy assimilation and growth. The corals take what they get and make due as best they can with the light waves we provide.

Obviously there is an optimum spectrum that we could provide that would allow maximum growth and health, we typically assume that "Sun Light" or day light is the optimum but that isn't necessarily the case if we are trying to maximize utility and minimize wasted (unuseable) light from our fixtures to the corals.

Different corals are likely to have different optimum spectrums, to boot, but the energy it would take to figure out and demonstrate this concept is far beyond the reach of the average reefer, and may be out of the grasp of science to measure with any great repetability.

The pigments that gather the light for photosynthesis can be present in many different ratios inside of a coral and I believe that these ratios will/can change over time.

But yes, useful light energy in the spectrum isn't the same across as the color changes. I have read that PAR isn't a truly useful measurement for photosynthetic light energy but it can serve as an indicator of the general amount of energy that is being provided. More needs to be learnt, and I suspect that some folks have a much better grasp of the issue and the difficulties of measuring useful light than I ever hope to achieve.

And that is why full spectrum MH, a "reasonable" replication of sunlight is so attractive for my tanks, and a lot of energy is obviously wasted growing algae along side the corals that I hope will thrive.

 

[Troylee]

He lives in Vegas, of course he has a nice tan!

That’s a fact! Haha

 

[Lasse]

Here is the spectra of my 6500 K LED. If your arguments are right - 6500 LED will be more effective than 6500 MH.

My picture of the aquarium shows rather good how it looks for my eyes - it is white not blue. I run Mitras Bar 2 and they is among the only that have RGB LEDs. and if I turn them to give 6500 K the spectra will look like this

IMO - the K has no importance

FYI - corals do not have Chlorophyll B - Among the chlorophylls they can have Chlorophyll A and/or C. And to this - there is more pigments that are involved in photosynthesis. But it is not the energy level in blue light that make blue light best suited - it is the absorption spectra of the proteins involved in photosynthesis that is important. Below is the absorption spectra of 5 proteins involved in photosynthesis in corals (there are more proteins involved but these is the most important) From here

Once again - For the photosynthesis in the action centra - its only 680 and 700 nm that´s important. Other wavelengths - in spite of their basic energy - must be converted into these wavelengths - hence energy losses that are greater than the energy difference between different wavelengths

About other wavelengths - please see this

General DIY LED thread

I like it. It's unique

www.reef2reef.com

and this

Coral Color Management｜BlueHarbor

This is a coral color management theory created by scientifically understanding the color of coral from an optical perspective.

www.blueharbor.co.jp

Sincerely Lasse

 

[JoshO]

Here is the spectra of my 6500 K LED. If your arguments are right - 6500 LED will be more effective than 6500 MH.

My picture of the aquarium shows rather good how it looks for my eyes - it is white not blue. I run Mitras Bar 2 and they is among the only that have RGB LEDs. and if I turn them to give 6500 K the spectra will look like this

IMO - the K has no importance

FYI - corals do not have Chlorophyll B - Among the chlorophylls they can have Chlorophyll A and/or C. And to this - there is more pigments that are involved in photosynthesis. But it is not the energy level in blue light that make blue light best suited - it is the absorption spectra of the proteins involved in photosynthesis that is important. Below is the absorption spectra of 5 proteins involved in photosynthesis in corals (there are more proteins involved but these is the most important) From here

Once again - For the photosynthesis in the action centra - its only 680 and 700 nm that´s important. Other wavelengths - in spite of their energy - must be converted into these wavelengths - hence energy losses that are greater than the energy difference between different wavelengths

About other wavelengths - please see this

General DIY LED thread

I like it. It's unique

www.reef2reef.com

and this

Coral Color Management｜BlueHarbor

This is a coral color management theory created by scientifically understanding the color of coral from an optical perspective.

www.blueharbor.co.jp

Sincerely Lasse

With regards to the 6500 LED I agree that you could in theory run only those, provided your par is higher than it would be for a much bluer 20k spectrum, as the ratio would be off.
I would hazard a guess and say that the ideal spectrum would be one that encompasses those peaks on your third imagine. Achieving the correct par with that spectrum would likely be optimal, anything else added after is purely aesthetic and extra unused energy.
We know that water filters out wavelengths of light as depth increases, so there is also the practical arguement that despite what is used in plant photosynthesis corals may not be able to use these wavelengths in the same way.
You're clearly incredibly educated on this subject, so I very much appreciate your input. From a purely practical perspective, based off of numerous studies I've been reading of late, is there a reason that the blue wavelengths seem to be most effective?

 

[Lasse]

From a purely practical perspective, based off of numerous studies I've been reading of late

It could be good to get links to these studies

Most photosynthetic corals that we have in aquarium exist from 5 meters and upwards. In these depths not so many wavelengths have been out filtrated. The normal "filtration" schema is from clean oceanic waters - it has been showed that the penetration is different in coastal waters - in open oceanic water 480 nm transmit best but in coastal zones 560 nm green/yellow transmit best. Please also see this

Figure from here

A: Radiation, Open ocean and costal water

Corals reefs is costal water and the penetration will be altered because of plankton and organic matter. Because of the spectra in water down to 5 m - corals needs sunscreen and protection That is the reason for all colourful pigments and floucence. In this article is it discussed and explained,

Sincerely Lasse

 

[CBonito]

It could be good to get links to these studies

Most photosynthetic corals that we have in aquarium exist from 5 meters and upwards. In these depths not so many wavelengths have been out filtrated. The normal "filtration" schema is from clean oceanic waters - it has been showed that the penetration is different in coastal waters - in open oceanic water 480 nm transmit best but in coastal zones 560 nm green/yellow transmit best. Please also see this

Figure from here

A: Radiation, Open ocean and costal water

Corals reefs is costal water and the penetration will be altered because of plankton and organic matter. Because of the spectra in water down to 5 m - corals needs sunscreen and protection That is the reason for all colourful pigments and floucence. In this article is it discussed and explained,

Sincerely Lasse

Very interesting.

 

[Doctorgori]

As the title implies, have we been wrong the whole time about the energy we provide our corals?
I was doing some digging, recently, into journals to better understand what is truly the optimum lighting for Acropora and stumbled across a study which assessed the influence of different Kelvin metal halides on the growth of Acropora Solitaryensis. They studied 5, 10, 15 and 20k temperatures, all with the same PAR value...guess what came out on top? The 20k...the most blue of all the spectrums. I was a little bit baffled by it as we always hear full spectrum is likely to grow corals quicker (anecdotal hobbyist evidence). So I dug a little deeper...here goes.
Light energy is in the form of waves. With the shortest, highest frequency at the UV end of the spectrum and longest lowest at the red end.
PAR is the measurement of the number of photons hitting an area in a given time frame that comes from the range of light which is considered photosynthetically available (I might have worded slightly wrong but hopefully you get the gist). There is no mention of the energy said photons provide, so here is where it gets interesting.
Let's say we've got 200 par of 420nm (blue) light and on another system we have 200 par of 570nm (yellow) light. From the way the hobby has described par these should equate to the same energy levels, correct? Wrong!!
If we go back to what I said earlier about the length and frequency of the light waves then you'll remember that I said blue are shorter and higher frequency. This means that each photon of blue light has more energy than it's friend the yellow photon.
This means that if we base our measurements purely on a par reading, and neglect to factor in spectrum, then we aren't going to be giving our corals the energy we expect!!

I think what you are saying is coral use more of the blue “spectrum” which is the actual measure of the photon wavelength/ energy. …. “ Kelvin” I think of as a color temperature measurement
“ White” is a composite color and saying corals don’t “need” white light is misleading as white light always contains blue, in fact you can’t have white light without blue
( the history of leds)

…odd factoid: contrary….some have indicate faster growth towards red … fwiw

added: blue just penetrates deeper and is more available at greater depths

 

[Doctorgori]

Grade them according to what??? We used 6500k haldies for many years there wasn’t any blue leds and very few vho’s to help with a blue spectrum.. corals grew just fine then.. actually grew great.. I’d put a 6500k up against any led today running only blues and it would blow them away.. that’s been my experience anyways. Granted the corals are brown and ugly haha! But they grow like weeds.

I’ve been saying this ever since the 90’s
again see history of blue led