A new metric on the rise.

[oreo54]

Gee, even before the ink is dry on PAR and PUR, they want to change things..

Last November, we published a detailed article about the work of the ASABE that had begun back in 2015 and that by last year had become a three-part proactive effort on standards development. As our article described, the first priority was definition of metrics and a new plant biologically active radiation (PBAR) radiometric band that spans 280–800 nm — covering the ultraviolet (UV) region below human visual sensitivity and the far-red region above.

http://www.ledsmagazine.com/horticu...-standard-for-led-horticultural-lighting.html

But UV light is now known to impact plant morphology. And the far-red region can impact seed germination, flower induction, plant height, and leaf expansion. The new standard will add new metrics in those regions.

Just an FYI....
PBAR meter anyone?

 

[mcarroll]

I'm sure it's useful to someone. Cool!

But as the PBAR folks (who???) agonize over that level of minuteness, we still have 90% of the folks in our little hobby not using any light meter at all. Not even a #lux meter, which can cost next to nothing and which can tell you almost everything you'd need to know for our purposes.

90% is much better than it was even 5 years ago, but the point still stands – wa-a-ay more folks need to have a light meter.

 

[mcarroll]

Gee

Oh no! You may have missed the sweetest quote in the lead-in:

the first in a series of three planned standards

(emphasis mine)

So eventually we'll have lux, PAR, PUR, PPFD, PBAR...maybe to be followed by PBS and PBJ.

 

[oreo54]

More like PMS............PTS...D

 

[mcarroll]

Looking at 200-800nm light (vs just visible light) will be a good thing for folks that actually need something like this. I'm sure Kessil would like us to be familiar with PBAR.

 

[oreo54]

Don't think Kessil wants you to "look" at anything..

 

[jda]

I am for anything that measures 350 to 800nm - I am convinced in my smallest-of-small brains, that this whole spectrum matters. Bring it on.

 

[Lasse]

I am sure that it will come some results that will give us a better and broader understanding of the way light affect our corals. Not only outside PAR but also inside and for wavelengths that´s not normally of so much interest in the hobby.

Green as an example. It´s not the most effective wavelength according to photosynthesis but these photons can penetrate living tissues, hence give photosynthesis in deeper layers and for leaves (in terrestrial plants) further down from the canopy. It´s easy to show this. As a clarification - the experiment was done in a dark room

From my build thread:​

There is also some prove for green photons can go trough leaves and hence make some photosynthesis rather low in the canopy. I got an idea – I can test that. I took my headlight (a strong phosphorus coated white LED) and hold it above a rather thick green leave from one of my wife's potted plants. The result you can see in the pictures below. From the upper side – there is reflecting many green photons – because the green colour of the leaf.

But how its look on the backside of the leaf – there is no light or reflected green photons there. If all photons are reflected (green) or absorbed (all others) it should be black on the backside. If the backside has any colour in this experiment – it means that the photons of that special wavelengths (read colour) has travel through the leaf – look self for the result.

I have never, ever before proved a theory so easy as I did in this case. Green photons can travel through plants cells in a way that others do not! It means that leaves further down in a tree can use green wavelengths – the red and blue is already absorbed.

Any importance’s for corals: For stony corals - at least because if it go through the living tissues - it will be reflected by the white skeleton and hence doing another run.

Sincerely Lasse

 

[jda]

Lasse - could this at least partially explain why light sources like T5 and MH appear to have less color loss on the underside of the coral, even with the same coverage? Could the higher amount of green light go through the tissue and provide nutrients to the other side of a branch in a "wrap" type of fashion?

 

[saltyfilmfolks]

I am sure that it will come some results that will give us a better and broader understanding of the way light affect our corals. Not only outside PAR but also inside and for wavelengths that´s not normally of so much interest in the hobby.

Green as an example. It´s not the most effective wavelength according to photosynthesis but these photons can penetrate living tissues, hence give photosynthesis in deeper layers and for leaves (in terrestrial plants) further down from the canopy. It´s easy to show this. As a clarification - the experiment was done in a dark room

From my build thread:​

There is also some prove for green photons can go trough leaves and hence make some photosynthesis rather low in the canopy. I got an idea – I can test that. I took my headlight (a strong phosphorus coated white LED) and hold it above a rather thick green leave from one of my wife's potted plants. The result you can see in the pictures below. From the upper side – there is reflecting many green photons – because the green colour of the leaf.

But how its look on the backside of the leaf – there is no light or reflected green photons there. If all photons are reflected (green) or absorbed (all others) it should be black on the backside. If the backside has any colour in this experiment – it means that the photons of that special wavelengths (read colour) has travel through the leaf – look self for the result.

I have never, ever before proved a theory so easy as I did in this case. Green photons can travel through plants cells in a way that others do not! It means that leaves further down in a tree can use green wavelengths – the red and blue is already absorbed.

Any importance’s for corals: For stony corals - at least because if it go through the living tissues - it will be reflected by the white skeleton and hence doing another run.

Sincerely Lasse

Have you examined the spectrum emitting through the leaf. Yes, it appears green, but....

Both blue and red ends can be filtered, but some of it is not , in general.
Ime , with some shade plants running in the low pars , 25-50 and likely less , it doesn’t take much.

Gee, even before the ink is dry on PAR and PUR, they want to change things..



http://www.ledsmagazine.com/horticu...-standard-for-led-horticultural-lighting.html



Just an FYI....
PBAR meter anyone?

Oy.

 

[Lasse]

Have you examined the spectrum emitting through the leaf. Yes, it appears green, but....

Both blue and red ends can be filtered, but some of it is not , in general.
Ime , with some shade plants running in the low pars , 25-50 and likely less , it doesn’t take much.


Oy.

The test was done with a Phosphorus covered LED.

2 minutes ago I did the same test with a LED with 420,430 and 445 nm (12 W) directly to the upper side of the leaf. Black on the backside. Did it also with 630 nm red and 660 nm red. red is known to penetrate a little and the leaf backside was a little orange for 630 and a weaker orange for 660 nm. Could not take a photo. But try to do it by your self. The red sources was also around 10 W

Sincerely Lasse

 

[Lasse]

Lasse - could this at least partially explain why light sources like T5 and MH appear to have less color loss on the underside of the coral, even with the same coverage? Could the higher amount of green light go through the tissue and provide nutrients to the other side of a branch in a "wrap" type of fashion?

I do not know that and have no idea about it.

Sincerely lasse

 

[oreo54]

Lasse - could this at least partially explain why light sources like T5 and MH appear to have less color loss on the underside of the coral, even with the same coverage? Could the higher amount of green light go through the tissue and provide nutrients to the other side of a branch in a "wrap" type of fashion?

Probably mostly due to glass reflections................. Even w/ great reflectors you are still dealing w/ a 360 degree light source..
http://www.archlighting.com/technology/leds-understanding-optical-performance_o

 

[Lasse]

Probably mostly due to glass reflections................. Even w/ great reflectors you are still dealing w/ a 360 degree light source..
http://www.archlighting.com/technology/leds-understanding-optical-performance_o

My first thought too. If this is the explanation - the new LED fixtures with diffusers probably will do the same. But I´m not sure. I

Sincerely Lasse

 

[jda]

That rings a bit hollow to me since the people who do not run lenses still have this issue. Anyway, thanks for the response.

 

[oreo54]

That rings a bit hollow to me since the people who do not run lenses still have this issue. Anyway, thanks for the response.

most "native" diodes are still lens-ed at 120 degrees or so.............
Much of the power is probably w/in 100 degrees or so..
@90 lensed.. most is in ..say..80 or so.

 

[saltyfilmfolks]

most "native" diodes are still lens-ed at 120 degrees or so.............
Much of the power is probably w/in 100 degrees or so..
@90 lensed.. most is in ..say..80 or so.

I don’t have the issue. All led.
It’s not the tool. It’s how it’s used. IME.

 

[Lasse]

That rings a bit hollow to me since the people who do not run lenses still have this issue. Anyway, thanks for the response.

I know people that run a combination of blue and white 3 W LED spread out over the whole surface area of the aquarium and get growth the way you describe for MH and T5. But the white LED contain much of green wavelengths so....... I have not any white LED only monochrome LEDs and I have growth even there it is no direct light from above. But since 2 months ago I have add 2 T5 bulbs - and do notv remeber how it looks before... Hence I do not role out your thoughts - you can be right - but I just do not know for the moment

Sincerely Lasse

 

[jda]

Lasse, thanks. I was mostly talking about the glass reflection, but I appreciate the response.

There is something about the spectrum in other sources that does something different. Instead of looking for what it is, or assuming that it is needed, it is the same bunch of excuses like lenses, light bouncing, and the other type of stuff yet the only real improvements have been to add in more spectrum that was previously forsaken. Maybe it is as simple as every wavelength matters and that evolution and adaptation does not waste anything, even if there are not studies to show us.

In every true piece of science, the "norm" is the norm until it is disproven. In the case of aquarium lighting, this trend reversed based a few terrestrial plant papers, what some manufacturers choose to sell and maybe a few almost-scientific studies. Now you have to prove that stuff that exists in nature and other light forms should be added back in. The answer should not be "we need to prove that something needs green spectrum" it should be "stuff thrives with massive amounts of green spectrum in nature, so we need to prove that it does not need it."

I like the PBAR concept because it includes a lot more of the waves that are probably of value in a difficult ecosystem where probably not much has been left to waste by nature and evolution.

 

[oreo54]

There is something about the spectrum in other sources that does something different

Naaahh not buying it ..no magic photons...
nothing here that can't be approximated w/ LEd's