How do the different light spectrums impact corals?

[Karen00]

This is a great question. I'm a noob and lighting is the area I'm researching now (just finished with water parameters) so I probably would've asked this as well at some point.

I want to add in... Does it matter where the corals sit in the wild? For example.... My understanding of light is that Red, yellow and others in this spectrum are quickly filtered out of the water because of their short wavelength so the deeper you go the more blue it gets until there is no light.

Sooo... Is it reasonable to think that corals that sit high up in the water, near the surface, or those that live in tidal pools might actually use red, yellow, etc as well as blue whereas those further down would most likely use just the blue?

Obviously it's possible the corals near the surface still don't use any of the red spectrum even though they have access to it. This is where expert advice comes in handy.

 

[Nano sapiens]

This is a great question. I'm a noob and lighting is the area I'm researching now (just finished with water parameters) so I probably would've asked this as well at some point.

I want to add in... Does it matter where the corals sit in the wild? For example.... My understanding of light is that Red, yellow and others in this spectrum are quickly filtered out of the water because of their short wavelength so the deeper you go the more blue it gets until there is no light.

Sooo... Is it reasonable to think that corals that sit high up in the water, near the surface, or those that live in tidal pools might actually use red, yellow, etc as well as blue whereas those further down would most likely use just the blue?

Obviously it's possible the corals near the surface still don't use any of the red spectrum even though they have access to it. This is where expert advice comes in handy.

The majority of wild corals are found in what we'd call 'deeper water'.

https://sioweb.ucsd.edu/projects/coralreefsystems/about-coral-reefs/biology-of-corals/

"...reef-building corals generally grow best at depths shallower than 70 m (230 ft). The most prolific reefs occupy depths of 18–27 m (60–90 ft)…".

The light field at such depths is predominantly blue, since blue light has the greatest depth penetration.

http://www.waterencyclopedia.com/La-Mi/Light-Transmission-in-the-Ocean.html

Shallow water corals can use some of the warmer hues for photosynthesis at lower intensities, but mostly they have to protect themselves from the high light intensity via pigment production, MMA 'sunscreens', polyp/tissue retraction/shading, etc.

I've experimented with red (660 nm) and I can say that in my mixed reef system that the corals do use it. When red is increased, kalkwasser usage is increased and when decreased, kalkwasser usage is decreased (all other variables stable and unchanged). The caveat here is that we are talking about relatively small amounts of red in the single digits and corals have to be very slowly acclimated to it. Many successful reef aquariums with very little to no red have shown that it isn't required by corals. I use it more for esthetic reasons as I prefer a somewhat warmer light field than is typical these days.

 

[Karen00]

The majority of wild corals are found in what we'd call 'deeper water'.

https://sioweb.ucsd.edu/projects/coralreefsystems/about-coral-reefs/biology-of-corals/

"...reef-building corals generally grow best at depths shallower than 70 m (230 ft). The most prolific reefs occupy depths of 18–27 m (60–90 ft)…".

The light field at such depths is predominantly blue, since blue light has the greatest depth penetration.

http://www.waterencyclopedia.com/La-Mi/Light-Transmission-in-the-Ocean.html

Shallow water corals can use some of the warmer hues for photosynthesis at lower intensities, but mostly they have to protect themselves from the high light intensity via pigment production, MMA 'sunscreens', polyp/tissue retraction/shading, etc.

I've experimented with red (660 nm) and I can say that in my mixed coral system that my corals do use it. When red is increased, kalkwasser usage is increased and when decrease, kalkwasser usage is decreased (all other variables stable and unchanged). The caveat here is that we are talking about relatively small amounts of red in the single digits and corals have to be very slowly acclimated to it.

Thank you for this great information! The mystery around lighting is starting to lift and all is being revealed! Just like it did when researching water parameters, dosing, etc. Haha!

 

[Nano sapiens]

Thank you for this great information! The mystery around lighting is starting to lift and all is being revealed! Just like it did when researching water parameters, dosing, etc. Haha!

There are a great many facets to coral reef lighting, spectrum being just one...

For a comprehensive deeper dive, take your time and peruse through this

https://reefs.com/magazine/light-in-the-reef-aquaria/


This is an interesting study related to your inquiry regarding deep vs. shallow water light fields and shows how wild coral (in this case Stylophora pistillata) has adapted to shallow (3 m) and deep (40 m) depths.

https://jeb.biologists.org/content/213/23/4084

SUMMARY
Depth 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 PAR and the spectral quality of the light. Here we used Stylophora pistillata colonies collected from shallow (3 m) and deep (40 m) water; colonies were placed in a respirometer under both ambient PAR irradiance and a filter that only transmits blue light. We found that the colonies exhibited a clear difference in their photosynthetic rates when illuminated under PAR and filtered blue light, with higher photosynthetic performance when deep colonies were exposed to blue light compared with full-spectrum PAR for the same light intensity and duration. By contrast, colonies from shallow water showed the opposite trend, with higher photosynthetic performances under full-spectrum PAR than under filtered blue light. These findings are supported by the absorption spectra of corals, with deeper colonies absorbing higher energy wavelengths than the shallow colonies, with different spectral signatures. Our results indicate that S. pistillata colonies are chromatically adapted to their surrounding light environment, with photoacclimation probably occurring via an increase in photosynthetic pigments rather than algal density. The spectral properties of the downwelling light are clearly a crucial component of photoacclimation that should be considered in future transplantation and photoacclimation studies.

Highlights the wide range of adaptability of corals that have allowed them to survive for millennia.

 

[jez]

I think the big take away from all of this is the adaptability of corals as long as they are not asked to adapt too quickly.

People now with Led always diss red end spectrum but us old timers with our 6.5k Iwasaki were pushing a comparatively large amount of red yellow and green spectrum into corals and having some of the first good successes with SPS corals back in the day. I then supplemented with the old Phillips o3 actinic to get a bit more blue and the corals appreciated that with growth spurts but it was short lived as old school actinic HO lamps were dead inside of three months. Always a growth spurt when you changed those tubes out.

It is also worth bearing in mind that lots of people talk about wild coral needs a lot of coral entering the hobby up till the ban was the mariculture stuff from Bali yes wild from other places but that is grown on shallow tables in anything from 3-8m from what I can make out and I did ask the big farmers when they started and that was the take away as they had to be easy to clean and manage.

I have several good friends who grow with Radion Pro g3/g4 and simply just run all channels at full so about 16k in old money ISTR and have corals growing like weeds.

In the end its the ability to adapt that is the most important thing.

 

[CherBear811]

Corals use most of the mid to low blue spectrum and the high end of the UV spectrum. They are far from useless. Red is beneficial and can be easily utilized, but the problem is it causes algae growth, as it's a major spectrum for macro growth. Red does make corals look better than just all blue though. I run twice as much red as I do green. Green is mainly to provide visual balance to the human eye.

 

[Karen00]

I think the big take away from all of this is the adaptability of corals as long as they are not asked to adapt too quickly.

People now with Led always diss red end spectrum but us old timers with our 6.5k Iwasaki were pushing a comparatively large amount of red yellow and green spectrum into corals and having some of the first good successes with SPS corals back in the day. I then supplemented with the old Phillips o3 actinic to get a bit more blue and the corals appreciated that with growth spurts but it was short lived as old school actinic HO lamps were dead inside of three months. Always a growth spurt when you changed those tubes out.

It is also worth bearing in mind that lots of people talk about wild coral needs a lot of coral entering the hobby up till the ban was the mariculture stuff from Bali yes wild from other places but that is grown on shallow tables in anything from 3-8m from what I can make out and I did ask the big farmers when they started and that was the take away as they had to be easy to clean and manage.

I have several good friends who grow with Radion Pro g3/g4 and simply just run all channels at full so about 16k in old money ISTR and have corals growing like weeds.

In the end its the ability to adapt that is the most important thing.

This is very interesting.

 

[Karen00]

There are a great many facets to coral reef lighting, spectrum being just one...

For a comprehensive deeper dive, take your time and peruse through this

https://reefs.com/magazine/light-in-the-reef-aquaria/


This is an interesting study related to your inquiry regarding deep vs. shallow water light fields and shows how wild coral (in this case Stylophora pistillata) has adapted to shallow (3 m) and deep (40 m) depths.

https://jeb.biologists.org/content/213/23/4084

SUMMARY
Depth 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 PAR and the spectral quality of the light. Here we used Stylophora pistillata colonies collected from shallow (3 m) and deep (40 m) water; colonies were placed in a respirometer under both ambient PAR irradiance and a filter that only transmits blue light. We found that the colonies exhibited a clear difference in their photosynthetic rates when illuminated under PAR and filtered blue light, with higher photosynthetic performance when deep colonies were exposed to blue light compared with full-spectrum PAR for the same light intensity and duration. By contrast, colonies from shallow water showed the opposite trend, with higher photosynthetic performances under full-spectrum PAR than under filtered blue light. These findings are supported by the absorption spectra of corals, with deeper colonies absorbing higher energy wavelengths than the shallow colonies, with different spectral signatures. Our results indicate that S. pistillata colonies are chromatically adapted to their surrounding light environment, with photoacclimation probably occurring via an increase in photosynthetic pigments rather than algal density. The spectral properties of the downwelling light are clearly a crucial component of photoacclimation that should be considered in future transplantation and photoacclimation studies.

Highlights the wide range of adaptability of corals that have allowed them to survive for millennia.

Very cool!

There are a great many facets to coral reef lighting, spectrum being just one...

For a comprehensive deeper dive, take your time and peruse through this

https://reefs.com/magazine/light-in-the-reef-aquaria/


This is an interesting study related to your inquiry regarding deep vs. shallow water light fields and shows how wild coral (in this case Stylophora pistillata) has adapted to shallow (3 m) and deep (40 m) depths.

https://jeb.biologists.org/content/213/23/4084

SUMMARY
Depth 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 PAR and the spectral quality of the light. Here we used Stylophora pistillata colonies collected from shallow (3 m) and deep (40 m) water; colonies were placed in a respirometer under both ambient PAR irradiance and a filter that only transmits blue light. We found that the colonies exhibited a clear difference in their photosynthetic rates when illuminated under PAR and filtered blue light, with higher photosynthetic performance when deep colonies were exposed to blue light compared with full-spectrum PAR for the same light intensity and duration. By contrast, colonies from shallow water showed the opposite trend, with higher photosynthetic performances under full-spectrum PAR than under filtered blue light. These findings are supported by the absorption spectra of corals, with deeper colonies absorbing higher energy wavelengths than the shallow colonies, with different spectral signatures. Our results indicate that S. pistillata colonies are chromatically adapted to their surrounding light environment, with photoacclimation probably occurring via an increase in photosynthetic pigments rather than algal density. The spectral properties of the downwelling light are clearly a crucial component of photoacclimation that should be considered in future transplantation and photoacclimation studies.

Highlights the wide range of adaptability of corals that have allowed them to survive for millennia.

Very cool reading! Thank you for finding this article!! I have added it to my rapidly growing library of content.

 

[Sallstrom]

About red light, around 660nm. You mean you might get uncontrolled macro algae growth if you add red light in a well working reef tank @CherBear811 ? I've seen this written a couple of times and I don't really understand that claim
In a reef tank we are blasting light to keep the corals happy and growing. We are adding more light then most organisms in the tank can use, if I have to guess. Why then should a little more red light do such a big difference? Red is a part of most white lights, so most tanks add red anyway.
Also, how much more growth in green macro algae gives red light compared to white or a blue at the same PAR level?

Anyway, I don't know the answers so I hope this didn't come out too harsh
We have used green house LEDs, with the red channel always running at some %, for 5+ years at my work(small public aquarium) and I can't say I've seen more algae problems under those light fixtures compared to under "reef lights". That is why I react on this claims.

 

[KyOsIBa515]

This has been heavily debated for over 20 years.

General consensus seems to be that corals are good enough using light that PAR is good enough, with something around 420nm optimal, near UV (e.g. 380+nm) being useful and greens and yellows less useful than red.

My personal opinion is near UV is useless, 400-500nm being useful with 430 being optimal. Green/Cyan won't help growth but can help with the 'Windex' look and make the tank look much more natural, but also makes it less colorful. Red can make fish and coral look a lot better, but is possibly harmful and definitely not helpful for coral.

I've been DIY-LED for almost 10 years now. When this first became an option, people recommended just using Royal Blues for growth, adding Cool Blue (450+nm) to balance the Windex look, and Cool White to see fish and other colors - as that was pretty much the only choices we had. Now there are tons of choices, and I've experimented with most of them - but I keep coming back to that original mix of 3 as the best (actual, using less warm or neutral white is IMO better looking than more cool white, but not a huge difference).

I personally like the all actinic look, especially in a small tank with the right corals that look good. But this is not for everyone, and I do have closer to a 12k look in my tank now. I will probably go bluer next time I make changes.

IMO corals react the same to MH, VHO and other lights - it is only the amount of photons and spectrum that matter. Of course, some people with very successful tanks will debate this on end, with people who swear only MH can grow the best looking SPS, VHO somehow glows better than LEDs, etc.

Bring this up next time time you are at a frag swap and you may start a fist fight.

This question is always a great one and furthermore opens a can of worms.
However, when dealing with corals reaction and overall growth to light I believe there is actual science to which option is the best for growth.

We study the growth in coral as photons in the wavelength that corals absorb and also drives the photosynthetic symbiotic relationship between algae, cynobacteria and coral (PAR). However, another key factor in photosynthetic symbiosis in corals is thermal energy which we do not take into account.

Water in the ocean has an amazing ability to capture the heat from sun and store that energy without effecting overall temperature. Between PAR and the thermal energy stored from heat it drives that process in a delicate balance by converting carbon dioxide to carbon and oxygen within the corals which stimulates and drives their growth. However, if any of the latter becomes out of balance the symbiosis breaks down and is also how corals become bleached.

Metal halides for growth you really cannot get a better option. They provide enough PAR and thermal energy in the water column through their heat to stimulate the best growth. The problem with metal halides is the heat produced in a small aquarium raises the temperature requiring a chiller and high power bill. The rest VHO T5’s and LED to follow as growth options.

To further that explanation some of the worst bleaching I have seen in corals in the aquarium have been from LED’s. Whether it was from the start or transfer lighting source...LED’s will produce awesome PAR through intensity but with very little heat. As explained in photosynthetic symbiosis that balance has been lost and causes the breakdown and bleaching. That is why especially with LEDs we ramp them gradually until the corals can adapt.

I personally like a hybrid system for growth. You get the best of all the worlds. Growth, color and aesthetics.

 

[Doctorgori]

just a side note: I’m right in the middle of building a BRS style “reef Fantasy/Fiction” experimental frag tank: one side lit with Blue the other side @ 5500K-ish ...
I got some/most of the stuff
My initial guess is it either won’t matter much or slight edge to red ...we’ll see

 

[CherBear811]

About red light, around 660nm. You mean you might get uncontrolled macro algae growth if you add red light in a well working reef tank @CherBear811 ? I've seen this written a couple of times and I don't really understand that claim
In a reef tank we are blasting light to keep the corals happy and growing. We are adding more light then most organisms in the tank can use, if I have to guess. Why then should a little more red light do such a big difference? Red is a part of most white lights, so most tanks add red anyway.
Also, how much more growth in green macro algae gives red light compared to white or a blue at the same PAR level?

Anyway, I don't know the answers so I hope this didn't come out too harsh
We have used green house LEDs, with the red channel always running at some %, for 5+ years at my work(small public aquarium) and I can't say I've seen more algae problems under those light fixtures compared to under "reef lights". That is why I react on this claims.

A little more red light isn't a problem. As I said, I use twice as much red as I do green because it has a benefit to corals and I like the slight purple look it gives in balance with the blue, over the yellow tint of the green. But ramping red up to equal blue is going to give you.... well, that's a fuge light, essentially. It is a fact that red is one of the best spectrums for macro. If you provide your DT with a lot of what algae needs to grow, balanced or not, it will take off. Try putting a fuge light over your DT and see what happens.

 

[Sallstrom]

A little more red light isn't a problem. As I said, I use twice as much red as I do green because it has a benefit to corals and I like the slight purple look it gives in balance with the blue, over the yellow tint of the green. But ramping red up to equal blue is going to give you.... well, that's a fuge light, essentially. It is a fact that red is one of the best spectrums for macro. If you provide your DT with a lot of what algae needs to grow, balanced or not, it will take off. Try putting a fuge light over your DT and see what happens.

Yes, done that. Worked fine, no algae explosion. Have a look below. Have you tried?

The white light fixture is a Heliospectra 600W LED for green houses. If you look at the reflection there are a lot of red diods. My guess is near half of the diods are red.

My point was that a well lit tank with "reef light" is excelent for macro algae already. And that the addition of red light in itself doesn't give you "macro algae problems".

But like you say, red light is very potent for algae, as for corals, so it should not be "overdosed"

Sorry if this got a bit off topic..

 

[CherBear811]

Yes, done that. Worked fine, no algae explosion. Have a look below. Have you tried?

The white light fixture is a Heliospectra 600W LED for green houses. If you look at the reflection there are a lot of red diods. My guess is near half of the diods are red.

My point was that a well lit tank with "reef light" is excelent for macro algae already. And that the addition of red light in itself doesn't give you "macro algae problems".

But like you say, red light is very potent for algae, as for corals, so it should not be "overdosed"

Sorry if this got a bit off topic..

Due respect, those don't look anything like fuge lights - and they are located directly over only coral colonies, where algae would have a difficult time establishing. Point those pink lights at your glass or sand and see what happens. That is barely pink tint at all. A fuge light is a flood of deep pink. Fact is, true fuge lights cause macro to grow a lot better, which is why they are used rather than other spectrums of light in a fuge. Again, and hopefully for the last time, I am not against using the red spectrum, and use more of it than most, with twice as much as I use of green. But if you provide blue and red in equal parts, it probably won't hurt the coral, but it will encourage algae growth (*** unless you have a beast of a light on your fuge with even more red that can out compete the DT for macro growth).

 

[Sallstrom]

Due respect, those don't look anything like fuge lights - and they are located directly over only coral colonies, where algae would have a difficult time establishing. Point those pink lights at your glass or sand and see what happens. That is barely pink tint at all. A fuge light is a flood of deep pink. Fact is, true fuge lights cause macro to grow a lot better, which is why they are used rather than other spectrums of light in a fuge. Again, and hopefully for the last time, I am not against using the red spectrum, and use more of it than most, with twice as much as I use of green. But if you provide blue and red in equal parts, it probably won't hurt the coral, but it will encourage algae growth (*** unless you have a beast of a light on your fuge with even more red that can out compete the DT for macro growth).

Sorry that I wasn't more specific. The majority of the diods are 660nm. And some 730nm, 450nm and 5700K (we ran the light fixture on the picture at 100%).
Pink is a mix of red and yellow, no specific wavelength. So perhaps the mix in this light looks pink. My guess is that light fixture would work very well for a refugium. Our phytoplankton cultures did like it a lot.
We run 8 of these units at the moment, and started up two of our temporary coral holding tanks with those. Still no macro algae explosions (but when using only these lights, we don't run the red at 100% - that would burn the corals. Yes, we have tried that as well).

Funny, I ran an experiment on just red and blue (50/50) for 6 months a couple of years ago Some corals even more then doubled their weight in 6 months. Not all species liked it. But Seriatopora really liked it. I can't remember us having algae problems. But we did have a good CUC.

I'm not saying you are against red light, but you keep saying that raising the level of red encourage macro algae growth in a display tank. And sure, in that case I say increased white or blue light also encourage macro algae growth in a reef tank
As long as you don't run too much red and keep a good team of grazers, I don't think you have to worry about algae.

 

[oreo54]

Another "review" sort of:

Red Light - Good or Bad for Corals?

These are two papers from over 30 years ago examining spectral composition and coral photophysiology: Kinzie, R.A., P.L. Jokiel and R. York, 1984. Effects of light of altered spectral composition on coral zooxanthellae associations and on zooxanthellae in vitro. Mar. Biol., 78:239-248...

www.reef2reef.com

Wheels on the bus go round and round.. Sorry light humor..

 

[jda]

Here is my oversimplified explanation that uses all three things that lights do, which is to give energy, reflect colors and then develop pigments/colors - all three are important for best results of growth and looks.

Daylight from 350 to 850nm for growth and color rendering and the blue it up until you like how they look - you can do both with different programs with LED, MH can do both in one package and you can also do both with a bunch of different T5 bulbs. I have seen true UV make a difference as well as IR to move energy between the photosystems, which is why I think that 350 to about 850nm matters.

 

[A. grandis]

Here is my oversimplified explanation that uses all three things that lights do, which is to give energy, reflect colors and then develop pigments/colors - all three are important for best results of growth and looks.

Daylight from 350 to 850nm for growth and color rendering and the blue it up until you like how they look - you can do both with different programs with LED, MH can do both in one package and you can also do both with a bunch of different T5 bulbs. I have seen true UV make a difference as well as IR to move energy between the photosystems, which is why I think that 350 to about 850nm matters.

Agreed!
It matters in the ocean, should matter in captivity.
And I strongly believe there is so much more to it that we didn't even get close to understand yet! Results is what we should look for.
I love science too, to explain the results.

 

[Dr. Dendrostein]

Hey guys I got a Zetlight UFO Z8, how you like them apples.....

 

[James Johnson]

Wow you guys are all over the place, it has to do with wavelengths, different colors of light have different wavelengths, depending on the wavelength of the light the color will penetrate the water better than others, due to this fact the deeper the water coral lives in the less colors of light can penetrate that deep, colors in the UV range are the best at penetrating water so depending on the depth corals prefer blue/purple Light because that is what they originally came from. From personal experience white light grows corals much faster but they tend to lack color and look more natural brown/tan dull reds and greens, blue light colors corals but doesn’t give you much growth And if your light is not powerful enough your corals will not get the PAR they need. So a full spectrum fixture that is more on the blue side 20k will give great results.