LED CRI suggestions for veg flower, or does it matter?

I doublechecked the ELG 240 is rated at 180W on 120V supplies.

http://www.meanwell.com/webapp/product/search.aspx?prod=ELG-240&mws=F53F34B19F590BD1

It is on page two under Rated power.

InTheValley said:

what does that mean?

in laymans terms,

Im tryin to hit Emerson with 3500K90cri and 730nm, with added 4000K80cri.

probably not enough 730, as its just Growmau puck, huh? 3.5x3.5 area

I personally think Emerson effect is magic if we hit it right, no?

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It means that the Emerson Effect occurs at LOW light levels. Its really that simple. If you want to grow with low light levels below 400 uMols then Emerson Effect will give you a boost. But at higher levels it just doesn't do much at all.

Humple said:

But I could be wrong.

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I think you are spot on.

wietefras said:

Exactly. Bugbee and others have done many tests and there really isn't much difference between different SPD's.

In 2014 people here started adding mono leds to the COBs to "improve" the spectrum. It died out quickly, because it quickly turned out to be easier/cheaper/more effective to simply add more COBs instead. So people returned to just COBs. Then new people enter the forum and they go hunting for the pot-o-gold at the end of the SPD rainbow. At some point they run tired of it too. New people come on the forum etc etc etc rinse and repeat.

It's just one of those things that people, especially those new to growing under "white" leds, think will make a massive difference, but it just doesn't.

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Interesting observation - and I tend to agree. I'll take a higher photon count over higher CRI any day of the week.

nfhiggs said:

It means that the Emerson Effect occurs at LOW light levels. Its really that simple. If you want to grow with low light levels below 400 uMols then Emerson Effect will give you a boost. But at higher levels it just doesn't do much at all.

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I'd like to thank you for pointing this out, I was totally unaware of that.

skoomd said:

I'd like to thank you for pointing this out, I was totally unaware of that.

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Probable purpose is to use the most of the diminishing light at sunset and the increasing light at sunrise. Mother Nature is smart like that.

hey i just really want to thank everyone for their time and answers to my questions, it's very much appreciated!

'Then new people enter the forum and they go hunting for the pot-o-gold at the end of the SPD rainbow"

my initial question was because of the cri options when ordering cobs, i had no idea it mattered.

Slinging PAR said:

Probable purpose is to use the most of the diminishing light at sunset and the increasing light at sunrise. Mother Nature is smart like that.

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or during heavy overcast skies.

nfhiggs said:

It means that the Emerson Effect occurs at LOW light levels. Its really that simple. If you want to grow with low light levels below 400 uMols then Emerson Effect will give you a boost. But at higher levels it just doesn't do much at all.

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Thanks nfhiggs,

so in a sense, stay under 400, with the right spectrum, we see better growth. But would be better in morning hours, then ease into highnoon, ( higher PAR ),, because Photosynthesis stops when the lights go out, so no sense in emerson effect at dusk, but add 730 nm for sleep.?

On right track?

I love this plant, lol, so much to it.

A bit of subjective observations from this run hunting for some nice mother plants I have noticed that the 90s have much better veg growth than the 80s. The 3000k CCT 80 CRI is not even doing as well as the blurple.

All at same ppfd to the canopy, same temps (low at 22-24c) with the only difference is that each plant is cracked from seed. It could be just luck of the draw and I am not jumping to anything conclusive yet but I will give it a test with vegging the clones under each to see if matters.

Check back in 4 months.

InTheValley said:

Thanks nfhiggs,

so in a sense, stay under 400, with the right spectrum, we see better growth. But would be better in morning hours, then ease into highnoon, ( higher PAR ),, because Photosynthesis stops when the lights go out, so no sense in emerson effect at dusk, but add 730 nm for sleep.?

On right track?

I love this plant, lol, so much to it.

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I have no doubt that would work. I just like to keep things simple.

i love the info that gets spread here. i have no problem learning from others, and in return i like to pay it back by doing the same for others. so i wanna thank everyone who helped me!

nfhiggs said:

It means that the Emerson Effect occurs at LOW light levels. Its really that simple. If you want to grow with low light levels below 400 uMols then Emerson Effect will give you a boost. But at higher levels it just doesn't do much at all.

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sorry to bring up an old thread but pretty much only small grows would try to do some "emerson effect" right? normal/larger grows wont care, and thus CRI 80 will suffice and CRI90 wont help (the larger/big light grows)

kdt15 said:

sorry to bring up an old thread but pretty much only small grows would try to do some "emerson effect" right? normal/larger grows wont care, and thus CRI 80 will suffice and CRI90 wont help (the larger/big light grows)

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PAR readings under various phosphor spectrums reveal a 10-12% difference in potential photons. If PAR alone determines growth rate we should all be flowering with 70CRI lamps. Increased efficacy due to elevated 660-690 range in 80 and 90 CRI lamps is the best candidate for explaining why the higher CRIs can do just as well. This is not the Emerson effect though but rather (probably) increased chlorophyll A activation which will suffer under lower CRI spectrums.

kdt15 said:

sorry to bring up an old thread but pretty much only small grows would try to do some "emerson effect" right? normal/larger grows wont care, and thus CRI 80 will suffice and CRI90 wont help (the larger/big light grows)

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Rahz said:

PAR readings under various phosphor spectrums reveal a 10-12% difference in potential photons. If PAR alone determines growth rate we should all be flowering with 70CRI lamps. Increased efficacy due to elevated 660-690 range in 80 and 90 CRI lamps is the best candidate for explaining why the higher CRIs can do just as well. This is not the Emerson effect though but rather (probably) increased chlorophyll A activation which will suffer under lower CRI spectrums.

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Yeah, CRI70 and 80 have not enough far-red to drive the Emerson effect. But with 3000°k/CRI90 you already get a useful amount of far-red. Far-red can not only boost the Emerson effect (along with deep-red) it also helps in other areas. It has, among other things, a regulating effect that compensates for differences in PS-A (I) and PS-B (II) and it helps with the leaf temps.

The regulating effect is a good point, and in theory there could be a net benefit to converting pfr during daylight hours. Whether this is related to Emerson is difficult to say, but there is obviously something happening. If there was no difference in electrical efficiency due to phosphor losses it might make 90CRI a more obvious choice.

The reason I don't suspect Emerson (at least not accounting for the majority) in my previous post is that absent any 400nm light the 660-690 band is the only region chlorophyll A has a chance to really soak up the photons efficiently and there's a big difference between 660-690 levels between 70CRI and 90CRI. I do agree that it's not conclusive though.

One follow up study I looked at some time ago indicated a drop of Emerson effect from 50% at 200 PPFD to 25% at 600 PPFD. I'm guessing on the PPFD because the study used einstein units and didn't specify /m2. I think the wavelengths used were 650 and 714nm. The curve indicated an approach to 0 at 1000 PPFD. It would be good to see something that dealt specifically with the light intensities we use, 700-1250 or something in that range.

Randomblame said:

Yeah, CRI70 and 80 have not enough far-red to drive the Emerson effect. But with 3000°k/CRI90 you already get a useful amount of far-red. Far-red can not only boost the Emerson effect (along with deep-red) it also helps in other areas. It has, among other things, a regulating effect that compensates for differences in PS-A (I) and PS-B (II) and it helps with the leaf temps.

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also the arcadia 13% far red.....I believe

Dave455 said:

also the arcadia 13% far red.....I believe

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Thats the spectrum of the Arcadia D3desert with 12% UVB. They are CRI90 but I don't believe this little bit means 13%. More like 3% between 650 and 750nm.



@Rahz
Yeah, with the usually used intensities of 800-1000μMol/s/m² there is only a little to no measurable Emerson effect. But with half that much light the effect could be already strong enough to make use of it.
You could get away with less watts in veg or above your mother plants for instance.
One can also try to use only 500μMol/s white + 150μMol/s deep/far-red in flowering and compare that with 650μMol/s of white only. Would be an easy experiment to proof if it works or not.
Unfortunately, there are no studies on how to use the Emerson effect wisely. Previous studies only show how it works and what wavelengths are needed but not how to take advantage of it.
But I'm pretty sure all the far-red effects work hand in hand and even if the Emerson effect is pretty low above 800μMol/s plants would profit from added far-red during the day.

Hmm, seems like could be a catch 22 for the vegetative stage if stretch is a concern, but that is likely where the most benefit would be seen for those flowering with high intensity. Probably no negatives to speak of with less stretchy varieties.

Regarding flowering do you think there would be any benefit to adding 730 to a 3000K 90CRI spectrum? Avoiding additional stretch would be a concern. If mixing high K low CRI with deep and far red becomes dominant due to electrical efficiency gains, same question applies... basically we'd be talking about exactly how much +700 is a good thing.

Rahz said:

Hmm, seems like could be a catch 22 for the vegetative stage if stretch is a concern, but that is likely where the most benefit would be seen for those flowering with high intensity. Probably no negatives to speak of with less stretchy varieties.

Regarding flowering do you think there would be any benefit to adding 730 to a 3000K 90CRI spectrum? Avoiding additional stretch would be a concern. If mixing high K low CRI with deep and far red becomes dominant due to electrical efficiency gains, same question applies... basically we'd be talking about exactly how much +700 is a good thing.

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If it is given during the light hours the stretch compared to CRI90 is probably negligible. I get more stretch mainly with longer EoD treatment. With stretchy sativas for instance I started using additional far-red when the stretch was almost done to avoid unwanted stretch. But since I have the UVB bulbs I get much less stretch than usual because of its blue part.
In the pdf about far-red they have used up to 90μmol/s per m². One would have to calculate how much far-red the CRI90 light already delivers and could supplement the difference with 730nm diodes.
With additional blue light you could counteract a too strong stretch. Blue light that hits the trunk directly reduces the stretch enormously. But it depends also a lot on the strain used.

Sad thing is, we know how the Emerson effect works but we don't have a proven method for how to make use of it. It is a pity that there is so little research in this area. After all, it seems to be a way in which plants(most of all plants) can get by with less light and thats especially important for the pros.
We semi-pros have to figure it out by trail and error and thats especially difficult because each strain behaves a little different. With indika dominant strains one get anyway less stretch and its done in two weeks from switch so there is not much speaking against far-red from the beginning. But with stretchy sativas it looks much different because they need up to 5 weeks to stop streching. So from my POV you need to figure out how much far-red you need for every new strain you have in your groom. Less stretchy strains = more far-red, more stretchy strains = less far-red.