InTheValley
Well-Known Member
This is exactly why i dont try to push my PAR above 500, and the benefit of using less nutes to sustain healthier growth overall,
80 vs 90 CRI... Convince me
- Thread starter 4ftRoots
- Start date
Michael Huntherz
Well-Known Member
Wat!?
Additionally, the initial question posed by the OP is epistemically flawed. I reject the premise that CRI is specifically relevant to either yield or quality. I don’t believe there’s any data to suggest any theory in these regards, nor was any effect postulated beyond the word “better,” which is not specific enough to be meaningful, much less useful.
Cheers, lovers!
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ChiefRunningPhist
Well-Known Member
Speaking on the topic of warm white CCT...
Its not a huge difference in SPD, but it seems that the differences do exist and that imo seem to be pointing towards a beneficial effect over a detrimental. But yes, I took the question as an opportunity to talk about green, what @Rocket Soul said about red shifting further is probably a big part of the differences too I'd imagine, it seems high CRI shifts/widens the red out a bit and increases green intensity.
EDIT:
Looking at the SPDs, it almost looks like the 757 V3's and probably all 3500k (or 3000k, I think this is a 3000k example SPD) have quite a bit of green, maybe 40%+? I guess I could digitize and find out. I'm tired I'll get back tmrw.
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ChiefRunningPhist
Well-Known Member
Red and blue light still make weight past 500μmol/s, just green makes more weight.. I think past 500μmol/s you'd just want to supp with a heavier green SPD, not nessecarily only green. But you're right the greater the wattage supplied the lower the yield rate, despite the actual total bud weight increasing.
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InTheValley
Well-Known Member
right on.
Michael Huntherz
Well-Known Member
Solid information, Chief, thank you for your insight.
Michael Huntherz
Well-Known Member
Norml56
Well-Known Member
By the time it isn't, we'll all be growing under the sun without worry.
pulpoinspace
Well-Known Member
11 votes to 0, seems like a lot of people are making the same big fucking guess.
good enough for me.
good enough for me.
Rocket Soul
Well-Known Member
Not quite true. For white phosphor led, yes, higher cri higher red. But some of the most extreme low ccts (nichia 2000k, blux 1750k) is actually only 80 cri cause they dont show as white, shows like orange.
But yeah, more red more growth, even in vegg
10WeekFlushBro
Well-Known Member
You probably have found it by now, but I will put it here for those who are wondering: The PPFDs were not the same, the plants receiving subcanopy lighting in this experiment received ~95µmol/s more than the control group (~500 µmol from the top). It is postulated by the authors that this increase in light is the reason for the increase in yield.
There are differences between the SCL Red+blue treatments and the red+green+blue treatments, which are touched upon in the article, interesting.
ANC
Well-Known Member
I am also a fan of green light, apart from the bits you were talking about, it also helps plants with shade avoidance. It is also used to reduce transpiration due to shading by other leaves.
Prawn Connery
Well-Known Member
OK, so I don't have the exact answer you require, but I've got a fairly close one. Those SPDs you posted are Nichias, which is what we're using for our High Light boards. The SPD below is a mix of CRI90 2700K V3-F1 (70% weighting) and Optisolis 2700K CRI97-98 (30% weighting). The RGB ratios are 11%, 37%, 47% with 5% FR.
@Rocket Soul 's link on the previous page is interesting about CRI vs McCree weighting, but it's a bit old and also ignores the fact that measuring PAR from 400-700nm does not tell the full story. CRI90 has almost three times as much Far Red as CRI70 - all things (generally) being equal.
Also, CRI90 is catching up in terms of efficiency and when multiplied by Quantum Efficiency of Radiation, the numbers are not too bad. Those 2700K V3-F1s, for example, are 55.4% efficient at QER 4.96 for 2.75 umol/j. The CRI98 Optisolis do pull the overall board numbers down to 2.5 umol/j but they do boost the overall CRI to 95.
Prawn Connery
Well-Known Member
I think the OP's premise is that within any particular LED family, higher CRI generally equates to a red shift towards lower wavelengths (better efficiency of photosynthesis), as well as increased cyan, more far red and a more even distribution of spectra across the range.
The argument then becomes: does more red, far red and cyan - as well as a more even spectrum - provide more benefit (in terms of yield or quality) than the impact on efficiency due to the different phosphor coatings?
That one I will leave for debate. But I will add there is no argument that higher CRI allows growers to see their plants "in a better light" (so to speak) due to the better colour rendition that can be beneficial in diagnosing nutrient and pest problems and other plant ailments.
ChiefRunningPhist
Well-Known Member
So guys.. A bit of a concession here.. After running the majority numbers this is what I'm getting...
It looks like actually (at least with Nichia 757V3 3k) the CRI80 has more overall green than the CRI90. It does seem that the CRI90 has a higher localized portion of the green, but on a whole, if my digitizing is accurate, the CRI80 has more green...
Boy do I feel stupid haha... Apologies
Attached are the .pdf's that show the calculations and graphs..
If you want a graph digitized for effeciency or weighted to the action SPD, lmk.. I can't post xcl files here or I'd just post the automated spreadsheet..
Still advocate for green, and high CRI, but at least in this instance (and probably every instance) they aren't 1 in the same...
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Michael Huntherz
Well-Known Member
Thank you for taking the time to make at an attempt at rigor, too few of us do, myself included. I am always interested in learning about light quality but it is not my primary interest. I really appreciate being able to learn more from threads like this, so thank you to everyone contributing here.
That said, I prefer to play the pragmatist on this stage;
I am strongly of the opinion that tweaking CRI is a very premature optimization in almost all real world situations. In this thread, and others like it, we are essentially asking these questions in a vacuum-world of spherical cows and gross oversimplifications.
People who are not strongly literate in science should keep in mind that these discussions are essentially academic in nature and not going to be useful in increasing your yield. Unless you’re already running an EXTREMELY tight ship, there are almost always better ways to optimize.
hillbill
Well-Known Member
Curious question, what happens to the energy generated by HPS in the infrared range? All things being the same with 1000w HPS and 1000w of LEDs or even a 1000 watt space heater and the LEDs not putting out any infrared.
Not having any depth in physics, having trouble getting this in my head but know they must all be the same.
Not having any depth in physics, having trouble getting this in my head but know they must all be the same.