Photosynthetically Usable Radiation - Sunlight, Metal Halide, LEDs

[Dana Riddle]

Got it, witchcraft!

I prefer to call it magic, but whatever.

 

[anit77]

Hey Dana, any plan to add T5 to the tests? Maybe just with the common ATI Blue+

 

[Dana Riddle]

I'm assuming absorbency also rolls off gradually below 400nm rather than straight to nothing?

Edit: I guess that is what the first image shows vs what the Seneye can read?

No, the second chart is the same information shown in the first, but in 10nm bandwidths. You astutely see where I'm headed with this - I'm preparing an Excel chart on wavelength/Seneye PUR for comparative purposes.

 

[Dana Riddle]

Hey Dana, any plan to add T5 to the tests? Maybe just with the common ATI Blue+

Hey there in Duluth Georgia. I shipped the fluorescent lamps and fixtures but haven't gotten around to unpacking them yet. So many lights, so little time.

 

[Dana Riddle]

I'm assuming absorbency also rolls off gradually below 400nm rather than straight to nothing?

Edit: I guess that is what the first image shows vs what the Seneye can read?

Yes. I've got a chlorophyll chart showing UV absorption. Somewhere. It trails off gradually more or less.

 

[anit77]

Hey there in Duluth Georgia. I shipped the fluorescent lamps and fixtures but haven't gotten around to unpacking them yet. So many lights, so little time.

Yea Duluth vs Dallas. So close yet so far... in Atl traffic.
I'm Adam for ARC. We meet at Shac's a couple years ago and had a few emails back and forth...

 

[Dana Riddle]

Yea Duluth vs Dallas. So close yet so far... in Atl traffic.
I'm Adam for ARC. We meet at Shac's a couple years ago and had a few emails back and forth...

Yes, of course. Excuse my poor memory. I've got MACNA and the Europe presentations behind me. PM me about ARC.

 

[jda]

If we are talking about usable radiation for "coral" then we are probably talking about a range from 350nm to about 850nm. "Coral" is a broad term that could be used to describe anemones, colonial anemones (Z&P), false coral (other softies), true coral (skeleton leavers) and the hard, light loving algae. Of course, this is a wide range of specimens with a wide range of proteins and zoox.

PAR meters do not read UV either... or IR. I would expect the Orphek to have a lot more output than what can be measured... MH is like this too.

 

[jda]

I guess in a nutshell, I see PUR as a wider range than PAR. PUR to me 350 to 850 for reef inhabitants whereas PAR is from 4oo to 700 which is the range of human vision (and too often the range of our though process).

 

[Dana Riddle]

Here's the PUR measurements as reported by the Seneye device. Compare these to the absorbance charts I posted earlier today. The trendline is the best fit I could get - 6th order polynomial. These LEDs are found in the Orphek luminaires. I also have other LEDs I haven't checked, some from Fluence Bioengineering and single 3-watt LEDs from SuperBrightLEDs. Bear in mind these are peaks of the LEDs and bandwidth extends to either side. For examples, the UV LED extends into the violet range, and the orange into red.

 

[madweazl]

So it is capturing UV; interested to see how far down it actually goes, assuming you do the same with the previously mentioned MH.

 

[Dana Riddle]

I'll take a photo of chlorophylls' absorption from the plankton book I have and post. Easier than wading thru all my Excel files.

 

[Dana Riddle]

I'm assuming absorbency also rolls off gradually below 400nm rather than straight to nothing?

Edit: I guess that is what the first image shows vs what the Seneye can read?

Here you go. From Shirley Jeffrey's works. I discussed things with her from time to time, and was saddened when she passed away. She did some cutting edge work, but male peers would not let her indicate she was female (by using her first name.) Instead, she had to publish as S. Jeffrey. OK, got that off my chest.

 

[madweazl]

Oh, that drops off quite quickly. Thanks for the scan

 

[Dana Riddle]

I wasnt able to see the images until I quoted you for some reason.

In case anyone else had the same issue:

I failed to note that absorbance was calculated using a polished Porites skeleton as the reference (instead of a Lambertian surface such as commercially available products.) Hence, we're seeing the true absorbance of corals tissue and zooxanthellae. This coral displayed zero fluorescence so that would not affect the result. I almost sold the PAM fluorometer using a red LED as the actinic source, glad I didn't as it is one of the few ways to examine absorbance without the interference of fluorescence. Sorry.
Got a little off track here.

 

[Jay Norris]

Same here, and I've been around reefing since we used candles to grow sps. Kids these days wouldn't believe it ! ;-)

What candles did you use, and what are their PAR readings?

 

[Dana Riddle]

An updated chart showing the PUR of 16 different LEDs as estimated by the Seneye device. The response to the 727nm LED might be to that light generated below 700nm. Radiation at or above 700nm is absorbed by Pigment 700 of Photosystem I and is important in preventing an electron bottleneck between it and Photosystem II.
Now, with that said, it is important to realize this chart doesn't tell the whole story. While radiation at, say 450nm, promotes photosynthesis it is also absorbed by protective xanthophylls that act as a pressure relief valve when light intensity is high. Also, combinations of light can enhance rates of photosynthesis (Google 'Emerson Enhancement Effect' if you're not familiar with this.) Not shown in the chart is the effect of IR radiation at about 840nm - this LED bandwidth by itself has an effect on the electron transport rates between photosystems, but disappears when combined with another bandwidth. I have no idea why. Comments welcomed!

 

[FLSharkvictim]

I am currently going to be running just 2 @Orphek new compacts on my SCA150 .
Depending on how it looks, I may add a pair of Reefbrite t-5's 50/50