Par Vs Color Temperature

chaoticreefer

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Hi Dana,
I have had this question on my mind for quite awhile and I just watched the youtube video of your presentation in San Diego (awesome presentation by the way), so it made me want to get my question answered even more. Shouldn't par levels be tied to light color temperature? Since higher color temperatures are bluer, which is what our corals absorb, shouldn't our pars be lower at 20k then let's say at 6500k since par is a measurement of all frequencies across all of visible light spectrum? Any info will be greatly appreciated.
 
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Ron Reefman

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Interesting question. And I misread it at first... I think.

You are asking if a 20,000K at a lower Par is as good as a 6500k at a higher PAR because the coral uses more blue spectrum for photosynthesis and the 20,000K light has more blue. In other words the PUR of 20,000K light is higher than the PUR of 6500k light. Is that another way of asking your question?

I think you are right, however, I think the difference in PAR would be small. And that corals use more than just blue spectrum which would make the difference even smaller.

But those are just my assumptions based on my limited knowledge. I'd be interested in hearing others thoughts... especially Dana's!
 

Graffiti Spot

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I assumed the 6500k bulb had a lot of blue in it but we just can’t see it with our eyes.
Op you got a link to his last speech?
 

Timfish

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Just to throw in my 2 cents, both PAR and Color Temperature are composite measurments. So two different light sources might measure the same but the spectrum may be different. Another factor to consider is different lighting technologies can have differential effects on corals so to some extent it might be kind of like comparing apples to oranges. We also need to consider individual coral species/genotype/variety photobiology, which it seems to me trumps any specific PAR or Color Temperature, what's optimum for one is not going to be optimum for another.
 
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chaoticreefer

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You are asking if a 20,000K at a lower Par is as good as a 6500k at a higher PAR because the coral uses more blue spectrum for photosynthesis and the 20,000K light has more blue. In other words the PUR of 20,000K light is higher than the PUR of 6500k light. Is that another way of asking your question?

Yes, that's another way to ask my question.
 
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chaoticreefer

chaoticreefer

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I assumed the 6500k bulb had a lot of blue in it but we just can’t see it with our eyes.
Op you got a link to his last speech?

I am sorry, I have never had "OP" tagged onto my avatar before so I don't quite understand it. Are you asking for the link to Dana's 2016 San Diego MACNA presentation? If so, here's the link.

 
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Dana Riddle

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I think the way to look at this is by comparing Photosynthetically Usable Radiation (PUR) of light sources. I use a Seneye device that has an algorithm comparing bandwidths and, generally, violet and blue LEDs have high PUR values (approaching 90% in some cases) while 'white' LEDs can be as low as 30%.
I have archived metal halide lamps for years and have 150, 175, 250 and 400 watt ballasts. Someday I'll get around to looking at metal halide PUR.
As for MH PAR, the higher the Kelvin, the less intense the PAR value simply because they don't contain metals needed to create full spectrum.
Tim is correct that photobiology differs among zooxanthellae clades. I'm getting a protocol worked out to examine ratio of blue to red light and how it affects zoox chlorophyll content. The hypothesis is that even small amounts of red will decrease zoox density/chlorophyll content.
 

Dana Riddle

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Bulk Reef Supply had a video of the San Diego MACNA presentation at one time. I suppose they still do. That was a most difficult project - took almost a year to complete. That one looked at alkalinity and rates of zoox photosynthesis, plus observations of corals in shallow Hawaiian tide pools. The Las Vegas presentation looked at coral coloration. I think BRS has that one posted as well.
 

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I am sorry, I have never had "OP" tagged onto my avatar before so I don't quite understand it. Are you asking for the link to Dana's 2016 San Diego MACNA presentation? If so, here's the link.



Yea that’s what I was wondering (op - original poster) thanks for the link! Even though I already have seen it, I thought you meant there was a new one out.
 

Dana Riddle

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Contrary opinion.. ;)


Ryan states that the interest in PUR is rather small. Agreed. And that the Seneye device only estimates PUR. True enough. However, I don't think we should ignore PUR until a lot more research is done.
 

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I don't think that people should rely on PUR too much either. Unless you don't care about color, looks or growth, then just doing photosynthesis is just a part of what you need lights for.

It is not nothing, but have a tempered view of the value of the measurement.

...and 6500k lights usually do have a lot of blue, just a lot of the other colors as well.
 

jda

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BTW - I hate the PUR measurement and the way that SenEye uses it. To me, the spectrum from about 350nm to about 850nm has value to and some sort of function to a wide range of proteins and systems. This whole range should be PUR, which is a larger subset of PAR. SenEye uses a smaller subset of PAR based on a partial range of a few proteins. I think that it is a dumb measurement, but I know that I am probably alone. /rant
 

oreo54

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Ryan states that the interest in PUR is rather small. Agreed. And that the Seneye device only estimates PUR. True enough. However, I don't think we should ignore PUR until a lot more research is done.

Agreed.. but no more than the "new" PAR definitions (unofficial AFAICT) that include <400nm and >700mn ;).
It is always good to have more data.
 

Dana Riddle

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Agreed.. but no more than the "new" PAR definitions (unofficial AFAICT) that include <400nm and >700mn ;).
It is always good to have more data.
Yup. PAR was defined by the transmission properties of plastics (that is, cutoff at 400nm and so on.)
 

techdef

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I think the way to look at this is by comparing Photosynthetically Usable Radiation (PUR) of light sources. I use a Seneye device that has an algorithm comparing bandwidths and, generally, violet and blue LEDs have high PUR values (approaching 90% in some cases) while 'white' LEDs can be as low as 30%.
I have archived metal halide lamps for years and have 150, 175, 250 and 400 watt ballasts. Someday I'll get around to looking at metal halide PUR.
As for MH PAR, the higher the Kelvin, the less intense the PAR value simply because they don't contain metals needed to create full spectrum.
Tim is correct that photobiology differs among zooxanthellae clades. I'm getting a protocol worked out to examine ratio of blue to red light and how it affects zoox chlorophyll content. The hypothesis is that even small amounts of red will decrease zoox density/chlorophyll content.

Hmmm, I’ve read thoughts on this before. Wondering aloud how that bodes for those of us trying to grow mangroves (or similar) which don’t thrive without more red spectrum?
I used to have a 6500k MH over a clam and mangrove which did great. Current setup however has a kessil H80 over the mangroves in the display tank. There’s certainly red spillover.

My only visual observation of the red lit area was a nem moved right into it. Probably a shallower water creature
 

jda

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Nearly everything that we have in our tanks was collected on one breath. Although some stuff can live deeper, you can bet 5 meters is a deep as most stuff was collected.

Tanks, rebreathers, etc. are saved for fish that get 10-100x as much money as corals wholesale. 30 meter fish can be several hundred from the diver whereas corals from 30 meters can be had shallower without the effort for a few bucks. Although most clams are also collected in shallow water, sometimes deeper water ones are collected with equipment... they are super expensive.
 

Butcher333

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I think the way to look at this is by comparing Photosynthetically Usable Radiation (PUR) of light sources. I use a Seneye device that has an algorithm comparing bandwidths and, generally, violet and blue LEDs have high PUR values (approaching 90% in some cases) while 'white' LEDs can be as low as 30%.
I have archived metal halide lamps for years and have 150, 175, 250 and 400 watt ballasts. Someday I'll get around to looking at metal halide PUR.
As for MH PAR, the higher the Kelvin, the less intense the PAR value simply because they don't contain metals needed to create full spectrum.
Tim is correct that photobiology differs among zooxanthellae clades. I'm getting a protocol worked out to examine ratio of blue to red light and how it affects zoox chlorophyll content. The hypothesis is that even small amounts of red will decrease zoox density/chlorophyll content.

Would like to see the PUR of metal halide Dan. There is a lot of PUR outside of the visible spectrum produced by MH.
I would be interested to see your findings on the ratio of blue to red as well. These kinds of studies exist for terrestrial plants.
Do you think you could get this research completed some time this week? :) thanks.
 

oreo54

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Would like to see the PUR of metal halide Dan. There is a lot of PUR outside of the visible spectrum produced by MH.
I would be interested to see your findings on the ratio of blue to red as well. These kinds of studies exist for terrestrial plants.
Do you think you could get this research completed some time this week? :) thanks.
A start.
upload_2019-2-14_12-35-12-png.977427



riddle_figure9.JPG

riddle_table2.jpg


Extended spectrum of 14000k mh
14000kmh.JPG


Extended, extended version.. Sorry not a reef bulb but assume the IR part is fairly universal. cmh4200k.JPG

"Life" beyond 700nm..
 
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