Tests regarding acropora growth.

[Phelipe's Ocean]

There are many things we discuss in this hobby and multiple trials have been done to see what works best with light sources, spectrums etc. but I would like to know have there been any trials to test if there would be faster growth with a longer light period shorter dark and vice versa? Im curious to see the effect of different extreme photo periods as I have heard from some corals grow in the day and other that they grow at night. There have been so many advancements in this hobby that I am very surprised no one has found a growth breakthrough yet wether it be some sort of serum/formula or something as simple as photo period.

 

[terri_ann]

Yes there has been but I cannot remember the details or where I read it, sorry. It's been awhile but WWC and a Canadian grower (cant remember the name, sorry) were compared. If my memory serves me correctly, one runs a shorter photoperiod and the other a longer one. Both had good growth. I believe it was based on intensity/PAR/PUR. Maybe another member here knows/remembers.

 

[ycnibrc]

Read Dana Riddle paper regarding lights and acopora growth. I believe he said 6hrs of full spectrum and intensity is best.

 

[jda]

You can find some studies, but they are not all that helpful. Dana has one using Porites from Hawaii and he readily admits that it will not scale to other types of corals - people were able to grow porites under incandescent light bulbs in fuges back in the day. If you do read them, pay attention to if they are peer reviewed and every detail - they might not be all that telling of what you will see in a tank.

He has another article that discusses TLI - Total Light Index. I could be getting that slightly wrong. Basically said that the light multiplied by the duration is just as effective in most scenarios... so 10 hours at 200 PAR is as good as 8 hours at 160... or so.

What I have found is that 10 hours of as much light as I can give acropora yields the best color and growth combined with low, but not too low building blocks, heavy fish feeding and constant element supply with CaRx. I have no doubt that all of these are linked... but I also believe that light is the most important factor since that is what truly feeds the coral.

 

[jda]

The Swedes did some testing on Poci or Stylos - this would be Lasse or Salstrom... I cannot remember which one. They seemed more like hobbyist type of tests moreso than a university controlled settings, but they also had the "feel" of being mostly real and trustworthy.

 

[Sallstrom]

We've done a couple of different scientific experiments on corals at The Maritime Museum & Aquarium in Gothenburg. Not published yet. But still done in a manner to be possible to publish and replicated.

But it's not easy setting up an experiment with Acropora and measure growth IMO. I've tried and failed
Instead we've mostly used Seriatopora hystrix, because they are easier to test for weight(we don't need to glue the colonies).

To test the things asked in the first post, the experiment setup will be a big challenge. I've done an experiment like that, same tank(long tank), walls between the lights, cover it all to avoid other light to get in, try to get the same flow etc, good number of replicas, good way to measure the growth etc. But that was with Seriatopora species and red light agains red + blue. The red + blue won

An easier way to do it in a regular tank might be to run one schedule for a period, measure before and after. Then run another schedule the same amount of days, measure before and after. Probably need to do it several times to get more reliable results.

 

[Sallstrom]

So short answer, no we haven't tested what's asked in the first post. Sorry for my long post above

 

[hart24601]

I have been curious about this as well and somethong that is similarly related, varying intensity of the lights over the photoperiod. I read the owner of orphek runs heavy clouds, which I had considered just a gimmick before but he claims they increase his growth. I then remember reading somewhere (I don't have links or am 100% sure of the data) that under high lighting corals photosynthetic pathways become overwhelmed quite quickly. I am curious if clouds (dimming) every half hour or so actually has any impact on growth at various light levels say 300 PAR (150 when cloudy) and 600 PAR (300 when cloudy) vs the total daily light amounts of both constant light and the total when cloud reduction is factored in.

 

[Phelipe's Ocean]

You can find some studies, but they are not all that helpful. Dana has one using Porites from Hawaii and he readily admits that it will not scale to other types of corals - people were able to grow porites under incandescent light bulbs in fuges back in the day. If you do read them, pay attention to if they are peer reviewed and every detail - they might not be all that telling of what you will see in a tank.

He has another article that discusses TLI - Total Light Index. I could be getting that slightly wrong. Basically said that the light multiplied by the duration is just as effective in most scenarios... so 10 hours at 200 PAR is as good as 8 hours at 160... or so.

What I have found is that 10 hours of as much light as I can give acropora yields the best color and growth combined with low, but not too low building blocks, heavy fish feeding and constant element supply with CaRx. I have no doubt that all of these are linked... but I also believe that light is the most important factor since that is what truly feeds the coral.

Im gonna check out the article havent read it before, interesting about the 10 hours at 200 and 8 at lower I didnt know that. I agree that light is very important and although some lights have proven to grow corals better im wondering if we shoukd start focusing on water chemistry. Playing around with extreme levels in expiremental tanks such as temperature, magnesium, and trace elements. Slightly off topic and may have a simple answer but how is it that for chaeto and algae we use lights with large peaks in the red, yellow, and green areas of the spectrum but for corals who rely on photosynthesis as well we try to remove red,yellow, and green from the spectrum? Has anyone conducted tests with growing coral under a grow light?

 

[Phelipe's Ocean]

I have been curious about this as well and somethong that is similarly related, varying intensity of the lights over the photoperiod. I read the owner of orphek runs heavy clouds, which I had considered just a gimmick before but he claims they increase his growth. I then remember reading somewhere (I don't have links or am 100% sure of the data) that under high lighting corals photosynthetic pathways become overwhelmed quite quickly. I am curious if clouds (dimming) every half hour or so actually has any impact on growth at various light levels say 300 PAR (150 when cloudy) and 600 PAR (300 when cloudy) vs the total daily light amounts of both constant light and the total when cloud reduction is factored in.

This is very interesting, how does he get this “cloud” effect? Automatic Dimming? Would be cool to see some trials with tanks running at lets say 14 hours a day under 200 par and one at 600 par for 8 hours. I never stopped to observe growth difference but I have noticed the higher the par you can get on a coral the better the coloration. Have you heard of Danny Horst? His peices are incredible, with most being above 800 par. Is there any info on the estimated par levels of the ocean?

 

[hart24601]

This is very interesting, how does he get this “cloud” effect? Automatic Dimming? Would be cool to see some trials with tanks running at lets say 14 hours a day under 200 par and one at 600 par for 8 hours. I never stopped to observe growth difference but I have noticed the higher the par you can get on a coral the better the coloration. Have you heard of Danny Horst? His peices are incredible, with most being above 800 par. Is there any info on the estimated par levels of the ocean?

Yep, it's an automatic dimming function the program can do, and other brands of LEDs too. I think with the orphek it kicks in 3 times an hour for 5 min each. I personally found a shift in many acro colors around 300 PAR.

@Dana Riddle any thoughts on cloud functions as it relates to photosynthetic capacity and giving an intensity reprieve or is the time/intensity reduction not significant?

 

[Sallstrom]

Im gonna check out the article havent read it before, interesting about the 10 hours at 200 and 8 at lower I didnt know that. I agree that light is very important and although some lights have proven to grow corals better im wondering if we shoukd start focusing on water chemistry. Playing around with extreme levels in expiremental tanks such as temperature, magnesium, and trace elements. Slightly off topic and may have a simple answer but how is it that for chaeto and algae we use lights with large peaks in the red, yellow, and green areas of the spectrum but for corals who rely on photosynthesis as well we try to remove red,yellow, and green from the spectrum? Has anyone conducted tests with growing coral under a grow light?

We tested photosynthesis(oxygen production under 2 h) on Seriatopora hystrix and Montipora sp. under different wavelengths in a lab. 420nm and 450 "won" most of the tests, but not by very much. Red, 660nm, was close to blue. Green was a bit lower oxygen production compared to red and blue, but still not low. No published article yet.
So yes, I think most corals can use green and red light.

But greenhouse LEDs might use a lot more red than blue.
The discussion has been something like this: blue light makes corals tolerate red light better. Take away the blue wavelengths and the coral doesn't seem to tolerate red light as much.
I don't have the knowledge behind this, so please correct me if I'm wrong.

But since I like to try stuff and we got a couple of greenhouse LEDs on loan from the company Heliospectra, I put a 600W fixture over our reef tank. All channels on 100%. It's been there for three years now and the corals are doing fine. But, important is that the corals also get light from metal halides in this tank, the lights from the lamps get mixed. So this is not a claim that corals do fine only with this LED.
You see the square reflection on the surface, that's from the greenhouse LED.

 

[Phelipe's Ocean]

We tested photosynthesis(oxygen production under 2 h) on Seriatopora hystrix and Montipora sp. under different wavelengths in a lab. 420nm and 450 "won" most of the tests, but not by very much. Red, 660nm, was close to blue. Green was a bit lower oxygen production compared to red and blue, but still not low. No published article yet.
So yes, I think most corals can use green and red light.

But greenhouse LEDs might use a lot more red than blue.
The discussion has been something like this: blue light makes corals tolerate red light better. Take away the blue wavelengths and the coral doesn't seem to tolerate red light as much.
I don't have the knowledge behind this, so please correct me if I'm wrong.

But since I like to try stuff and we got a couple of greenhouse LEDs on loan from the company Heliospectra, I put a 600W fixture over our reef tank. All channels on 100%. It's been there for three years now and the corals are doing fine. But, important is that the corals also get light from metal halides in this tank, the lights from the lamps get mixed. So this is not a claim that corals do fine only with this LED.
You see the square reflection on the surface, that's from the greenhouse LED.

Wow look at those colonies! How is growth for you under this grow light?

 

[Dana Riddle]

Yep, it's an automatic dimming function the program can do, and other brands of LEDs too. I think with the orphek it kicks in 3 times an hour for 5 min each. I personally found a shift in many acro colors around 300 PAR.

@Dana Riddle any thoughts on cloud functions as it relates to photosynthetic capacity and giving an intensity reprieve or is the time/intensity reduction not significant?

There are a couple of things to consider when we're discussing cloud cover and photosynthesis. First and most obviously is the function of photosynthesis in relation to light intensity. As we have discussed, a minimum amount of light is required to exceed the Compensation Point (where oxygen production by zoox meets their and the coral animal's requirement. In shallow water corals, this can occur very early in the morning.) The second milestone is the Saturation Point where an increase in light intensity does not result in an increase in photosynthesis (in Hawaiian tide pool corals, this happens mid-morning. The average Saturation Point of all corals in my database is about 225 micromol/m2/sec. but this depends upon the depth/light intensity the coral is adapted to. This could be merely an adaptive process or determined by the zoox type or clade - some types need light, while others do poorly in high light. The range of Saturation ranges from 77 micromol/m2/sec in Acropora divaricata at 40 meter depth to about 400 seen in Porites lutea at about 2 meter depth. Tridacna clams are a different story - no saturation was seen at 600.) As light intensity continues to rise, natural protective processes begin to shut down photosynthesis and this is called Dynamic Photoinhibition (DP.) DP can happen in late morning (if light intensity is high enough) and involves the conversion of xanthophylls (diatoxanthin and diadinoxanthin.) This conversion is dependent upon pH within the photo apparatus and is up-regulated in a few minutes. The backwards conversion takes much longer. Worst case is Chronic Photoinhibition (CP) where all protective processes are overwhelmed, and photo-damage occurs. Prolonged CP can be deadly.
Now, to answer your questions (and it depends upon light intensity.) If light is on the ragged edge of the Compensation Point, any reduction in light will not be beneficial photosynthetically. Light reduction won't make a lot of beneficial difference if the light intensity falls between the Saturation Point and the lower edge of Dynamic Photoinhibition. Recall that the down regulation of the protect xanthophyll takes many minutes, if not hours. If so much light is causing Chronic Photoinhibition, then a reduction should be long term.
I've got some comments to make about some odd observations made when exposing corals to red light. It has to do with the onset of Dynamic Photoinhibition. I'll get to this as soon as I can. Linda had major surgery yesterday and I am the primary care giver to her, two dogs and a reef tank.

 

[hart24601]

Really appreciate the reply and the time you took to answer. Doesn't sound like cloud functions are particularly worthwhile then since it takes so long for down regulation. Nailed my question exactly!


Hope Linda recovers soon and all goes well with her the tank and the dogs!

 

[Dana Riddle]

Really appreciate the reply and the time you took to answer. Doesn't sound like cloud functions are particularly worthwhile then since it takes so long for down regulation. Nailed my question exactly!


Hope Linda recovers soon and all goes well with her the tank and the dogs!

Thank you! I'll pass your comment on to Linda. She needs lots of moral support right now. OK, off to upstairs to check on her, walk the dogs....

 

[TexasTodd]

Thanks as always Dana. Hang in there, "caretaker" is a hard job.
Todd

 

[BradB]

I know from experience:
1) optimal growth is way shorter a photo period than optimal viewing
2) this matters a lot less than flow and alkanity

I like to see my tank, so I run 12 hours or longer. As a commercial grower, I might run 5 hours to cut the cost of electricity, but this is negligible as a hobbyist

 

[CC13]

Tagging along

 

[CC13]

Repost by accident.