LEDgardener

I think you mentioned you were doing a grow comparison of an 80 CRI led versus a 90 CRI led. I was wondering if you had taken ppfd measurements off both lights and if so which was higher?

Thanks!

kmb wrote: ↑

Thu Sep 07, 2017 5:48 am

I think you mentioned you were doing a grow comparison of an 80 CRI led versus a 90 CRI led. I was wondering if you had taken ppfd measurements off both lights and if so which was higher?

Thanks!

The 80 cri will produce higher lumens and I presume higher ppfd at a given amount of current compared to a 90 CRI lamp. It seems to me that it looks like led manufactures use filters to get to a higher CRI, hence reducing the amount of light the leds put out at higher CRI values.

It would be an interesting experiment though...

I don't have the hard data, but I had the chance to talk with a commercial grower who did an in-house experiment and reported that 90CRI more than compensated in overall efficacy for the lower lumen/watt efficiency.

So yes, this is a random stranger telling you about the not-peer-reviewed experience of another unknown stranger. But still, for what it's worth, my last lights were 3000+4000K@80CRI and my next lights will be 3000K@90CRI. (My dilemmas: wait until the new mid-power Samsung comes out? Buy strips from DigiKey or have PCB's printed from an Alibaba supplier?)

NapalmD had a 80 cri vrs 90 cri 3k qb side by side going on RIU. I think he was one of the first 90cri qb testers for HLG. Robin sent me to it when asking about the new boards. he asked what I though. after reading/looking thru I would most likely agree with your random stranger

http://www.rollitup.org/t/quantum-board ... wn.941168/

I'm thinking for my situation to go more color now... then later swap the 80s for 90s as base white. once more options are available in 90cri

Through my research of LED grows, it seems the higher cri does better. No testing of my own done, just what ive been reading

I just sprouted a bunch of banana pepper and jalapeno seeds and my goal for tomorrow is to come up with a way to build 3 little chambers to test 3 different Quantum Boards: 3000K 80CRI, 3000K 90CRI, and 4000K 80CRI.

If all goes to plan I'll have plants under lights by the end of the weekend and we'll see how they do. I'll see if I can get some PPFD measurements as well.

Of course if anybody feels generous enough to send me different lights at 80/90CRI I'd be happy to have a nice little experiment going with 2/4 tents

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Maxxor wrote: ↑

Wed Dec 13, 2017 4:43 am

I don't yet see the advantage of spending more for 90 CRI diodes when 80 CRI is already more efficient for indoor growing than nearly every other man-made light source. Seems like a cost/benefit fail.

That would depend on how you measure efficiency. 80CRI is definitely more efficient in producing light (lumens per watt). There's a growing body of anecdotal evidence (including on this blog!) that 90CRI could be more efficient in terms of plant growth (grams per watt).

COB LEDs, being arrays of blue LEDs coated with phosphor to achieve white light, emit less photons as more pigmented phosphor (coating) must be applied to achieve higher CRIs (color-rendering-index, a "score" representing how closely an object's color is reproduced by the light from the emitter).

However, the reason higher CRI LEDs grow weed better (if they do), is that... they contain what's missing from low CRI LEDs... the thing that makes color look washed out... the volume of RED (wavelength) light.

High CRI LEDs will have a red peak, way to the right - higher in the 600s (photo/deep/far red), than an 80 CRI LED.

This $20, 50v, 90CRI, Citi LED (048-1818) is most efficient around 150w and peaks at 630nm and intersects 680 at 60%:
...pretty close to this $34 Cree that way outperforms Cree's other 80 CRI offerings, but is only as efficient when driven below 50-60w.

So - although there are a fewer number of photons (overall and in the PAR range), the photons that exist are more efficiently used in photosynthesis for flowering.