LED Intensity vs Duration affects on coral color and bleaching

[b4tn]

I am still trying to wrap my head around intensity vs duration when it comes to lighting. I currently have Ocean revive lights set to 20 white Chanel and 85 blue Chanel. Blues begin ramping at 10 am and turn off at 10 pm. White/full spectrum start ramping 11am and turn off at 9pm. Blue not counting ramping time is full intensity for 6 hours and white is full intensity for 4 hours.

We all know that light that is to intense will bleach corals. But will intense light for to long of a duration affect coral color/bleaching? I am starting to think I need to dial back my light duration. Seems that most are in the opinion that corals only need 4-6 hours of light and mine just on the blue side are getting 6 hours of ramping time and 6 hours full intensity. Opinions?

 

[saltyfilmfolks]

Basically, we measure light for photosynthesis by how many photons hit a spot. UMOL.
So it’s a bit cumulative.
100 in an hour or ten in ten hours actually works.



So.... you can increase intensity OR duration.

However , as our tanks have different nutrient levels , we need to pay attention to the possibility that at longer or higher light they may run out of fuel for photosynthesis.

https://www.reef2reef.com/threads/h...d-i-dont-know-what-to-do.210035/#post-2401666

Sonthe Coral you got from a guy running 700 par on it for the same amount of time you do may not work for you and you need to grow it at 350 par because you have lower nutrients. Generally the coral will adapt.

This basically is why it’s reccomend to move corals arount in the tank. And slowly increase or decrease time or intensity For the tank.

It’s quite simple , but the why is complex.

Fwiw , it doesn’t matter what is producing the photon. Led or MH etc.

My tank at it’s best was only a 4-5 hr peak but was 13 hrs of viewing time or photoperiod with led.

 

[sbash]

Great question, have you ready any of Dana's articles published on Advanced Aquarist?

We had a brief discussion on this a while back:
https://www.reef2reef.com/threads/ideal-par-but-for-how-long.324114/#post-4065410

I make reference to this article:
https://www.advancedaquarist.com/2009/5/aafeature

What I got out of it (especially in reference to table 1), is that a 12 hour cycle is ideal. I don't 'ramp' my lights, so I can't comment on that, but I have noticed better growth since I extended from 10 to 12 hours of blue (8ish hours of white and mixed lights)...

 

[Oldreefer44]

Used to run a 10 hour cycle (Orphek v4's). Now I am trying to simulate what I think the corals would experience if they were in the ocean. 12 hour cycle ramping up quickly to 50 to 70% and peaking at 70 to 100%. Whites are on the lower end with blues and greens higher. Have noticed an increase in calcium use with the increase in light duration. Also use a cloud program the is heavier during peak lighting hours and lighter in what would be considered morning and evening hours. Have to say that while I cant say that I have seen a dramatic increase in growth I do see what I would consider to be healthier more robust coloration in about 2 thirds of my corals. Oddly, the only one that seems to disapprove is my green star polyps which is just fine with me.

 

[Dana Riddle]

I am still trying to wrap my head around intensity vs duration when it comes to lighting. I currently have Ocean revive lights set to 20 white Chanel and 85 blue Chanel. Blues begin ramping at 10 am and turn off at 10 pm. White/full spectrum start ramping 11am and turn off at 9pm. Blue not counting ramping time is full intensity for 6 hours and white is full intensity for 4 hours.

We all know that light that is to intense will bleach corals. But will intense light for to long of a duration affect coral color/bleaching? I am starting to think I need to dial back my light duration. Seems that most are in the opinion that corals only need 4-6 hours of light and mine just on the blue side are getting 6 hours of ramping time and 6 hours full intensity. Opinions?

Do you have any PAR numbers to share? If so, I'll calculate a Daily Light Integral (DLI) for you. Peak PPFD is fine, I can estimate the ramping.

 

[b4tn]

Basically, we measure light for photosynthesis by how many photons hit a spot. UMOL.
So it’s a bit cumulative.
100 in an hour or ten in ten hours actually works.



So.... you can increase intensity OR duration.

However , as our tanks have different nutrient levels , we need to pay attention to the possibility that at longer or higher light they may run out of fuel for photosynthesis.

https://www.reef2reef.com/threads/h...d-i-dont-know-what-to-do.210035/#post-2401666

Sonthe Coral you got from a guy running 700 par on it for the same amount of time you do may not work for you and you need to grow it at 350 par because you have lower nutrients. Generally the coral will adapt.

This basically is why it’s reccomend to move corals arount in the tank. And slowly increase or decrease time or intensity For the tank.

It’s quite simple , but the why is complex.

Fwiw , it doesn’t matter what is producing the photon. Led or MH etc.

My tank at it’s best was only a 4-5 hr peak but was 13 hrs of viewing time or photoperiod with led.

@saltyfilmfolks so thats actually interesting. I have a heck of a time getting my nutrient levels to be readable. I am not sure I would consider myself to be ULN becuase I can grow a scrubber out pretty well but notice that corals are lackluster in color. I wonder since nutrients are on the low side if I would benefit from less light.

Great question, have you ready any of Dana's articles published on Advanced Aquarist?

We had a brief discussion on this a while back:
https://www.reef2reef.com/threads/ideal-par-but-for-how-long.324114/#post-4065410

I make reference to this article:
https://www.advancedaquarist.com/2009/5/aafeature

What I got out of it (especially in reference to table 1), is that a 12 hour cycle is ideal. I don't 'ramp' my lights, so I can't comment on that, but I have noticed better growth since I extended from 10 to 12 hours of blue (8ish hours of white and mixed lights)...

Thanks for the links. I recently watched one of Dana's videos regarding light that showed that corals could grow and color well under lower lighting conditions and that intense light may actually stunt growth. But a lot of the articles start going over my head with the science involved lol.

 

[saltyfilmfolks]

@saltyfilmfolks so thats actually interesting. I have a heck of a time getting my nutrient levels to be readable. I am not sure I would consider myself to be ULN becuase I can grow a scrubber out pretty well but notice that corals are lackluster in color. I wonder since nutrients are on the low side if I would benefit from less light.



Thanks for the links. I recently watched one of Dana's videos regarding light that showed that corals could grow and color well under lower lighting conditions and that intense light may actually stunt growth. But a lot of the articles start going over my head with the science involved lol.

When I ran into troubles , I merely shortened or lengthend the peak time.

Keep in mind this definition of “intense” , we think bright, but in fact is more like grains of sand piling up. In this case , it’s photons.

 

[b4tn]

Do you have any PAR numbers to share? If so, I'll calculate a Daily Light Integral (DLI) for you. Peak PPFD is fine, I can estimate the ramping.

Thanks @Dana Riddle here is my most recent par readings. I did not read upper levels on the right hand side but it should be close to the same.

 

[b4tn]

When I ran into troubles , I merely shortened or lengthend the peak time.

Keep in mind this definition of “intense” , we think bright, but in fact is more like grains of sand piling up. In this case , it’s photons.

Thanks, I curious what Dana recommends but I’m thinking I will probably leave over all duration the same but start slowly reducing peak time and see how things look.

 

[Dana Riddle]

I am still trying to wrap my head around intensity vs duration when it comes to lighting. I currently have Ocean revive lights set to 20 white Chanel and 85 blue Chanel. Blues begin ramping at 10 am and turn off at 10 pm. White/full spectrum start ramping 11am and turn off at 9pm. Blue not counting ramping time is full intensity for 6 hours and white is full intensity for 4 hours.

We all know that light that is to intense will bleach corals. But will intense light for to long of a duration affect coral color/bleaching? I am starting to think I need to dial back my light duration. Seems that most are in the opinion that corals only need 4-6 hours of light and mine just on the blue side are getting 6 hours of ramping time and 6 hours full intensity. Opinions?

There are a couple of ways we can look at this - instantaneous PPFD and total light dosage during the photoperiod. I used the maximum PPFD I could read in your photo (347 micromole/m2/sec) for the instantaneous dosage - this is around the photosaturation point for many shallow water corals and unless your coral species are known to be deep water specimens, I wouldn't be concerned. I had to make some assumptions while calculating percentages of light intensity from the two channels but erred on the side of caution. In addition, it appears in your chart that the white channel is at full intensity for about 6 hours and I used this for the total light dosage calc. To make a long story short, the Daily Light Integral (DLI) is about 11 which is well below what shallow water corals can experience. My calculations are not perfect by any means as I would need further information but this is close enough. I would feel comfortable with this DLI number if it were my reef. As long as acclimation is made, bleaching shouldn't be an issue. Coloration on the other hand is produced by the coral and is often a response to light intensity (not always.) Your instantaneous PPFD is high enough at the maximum I see in your picture to induce a coloration response. It is not sufficient in the lowest readings and these should be examined on a case by case basis.

 

[saltyfilmfolks]

There are a couple of ways we can look at this - instantaneous PPFD and total light dosage during the photoperiod. I used the maximum PPFD I could read in your photo (347 micromole/m2/sec) for the instantaneous dosage - this is around the photosaturation point for many shallow water corals and unless your coral species are known to be deep water specimens, I wouldn't be concerned. I had to make some assumptions while calculating percentages of light intensity from the two channels but erred on the side of caution. In addition, it appears in your chart that the white channel is at full intensity for about 6 hours and I used this for the total light dosage calc. To make a long story short, the Daily Light Integral (DLI) is about 11 which is well below what shallow water corals can experience. My calculations are not perfect by any means as I would need further information but this is close enough. I would feel comfortable with this DLI number if it were my reef. As long as acclimation is made, bleaching shouldn't be an issue. Coloration on the other hand is produced by the coral and is often a response to light intensity (not always.) Your instantaneous PPFD is high enough at the maximum I see in your picture to induce a coloration response. It is not sufficient in the lowest readings and these should be examined on a case by case basis.

 

[b4tn]

There are a couple of ways we can look at this - instantaneous PPFD and total light dosage during the photoperiod. I used the maximum PPFD I could read in your photo (347 micromole/m2/sec) for the instantaneous dosage - this is around the photosaturation point for many shallow water corals and unless your coral species are known to be deep water specimens, I wouldn't be concerned. I had to make some assumptions while calculating percentages of light intensity from the two channels but erred on the side of caution. In addition, it appears in your chart that the white channel is at full intensity for about 6 hours and I used this for the total light dosage calc. To make a long story short, the Daily Light Integral (DLI) is about 11 which is well below what shallow water corals can experience. My calculations are not perfect by any means as I would need further information but this is close enough. I would feel comfortable with this DLI number if it were my reef. As long as acclimation is made, bleaching shouldn't be an issue. Coloration on the other hand is produced by the coral and is often a response to light intensity (not always.) Your instantaneous PPFD is high enough at the maximum I see in your picture to induce a coloration response. It is not sufficient in the lowest readings and these should be examined on a case by case basis.

Thanks so much for taking the time to calculate this out.

 

[ReeferA]

UPDATE:
While researching the intensity of light effect on corals, I came up on this study which was published January 2023:
Light affects physiological aspects of coral growth. However, it is unclear how light conditions (photoperiod, intensity, and spectrum) influence growth physiology. We examined the effects of various light conditions on skeletal growth promotion and the physiological mechanisms responsible for growth in Acroporid corals. Acroporid corals (Acropora tenuis, A. muricata, and A. intermedia) were reared for 2 months under various photoperiods (hours of light/dark = 8:16, 12:12, and 16:8) and light intensities (100 and 200 µEm−2 s−1). Growth was greater in all coral species under longer photoperiods and at higher light intensities. Next, we used a photoperiod of 16:10 (hours of light/dark) and 200 µEm−2 s−1 light of three spectral composition from a light-emitting diode. The growth of A. tenuis and A. intermedia increased with increasing wavelength. The symbiotic algae density increased as the photoperiod increased. Symbiotic algae density and chlorophyll content were affected by the light spectrum but were not associated with the degree of growth. Therefore, changes in light conditions can induce coral growth without changing symbiotic algae density or chlorophyll content. Real-time quantitative polymerase chain reaction analysis revealed that the level of carbonic anhydrase mRNA changed with coral growth, suggesting that light accelerates coral calcification via photosynthesis by algal symbionts.