It’s a dance between efficiency and spectrum. Photons are photons in the grand scheme of things.
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Ive read what people experienced in compare to 5000k in mums room and mean than its overall better to have that even for mumms (you can flower by them autos). 3500k is also very feer buds and grow of course
And what have written with one man in firma testing, 1750k is not so good as it seems, same results with 2700 if i remember his words correctly
just from my searching ive found as best 3000k 90cri as best for whatewer you want, and thats why ive made it 
But yes, for flowering there was a very known compare 80 with 90 cri and nothing about 70. About 70cri i have no data. Do you have xperiences? Theory doesnt interest me so much 
there is tons of theory sometimes
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It’s really difficult to decipher the spectrum charts in the datasheets when
it comes to 4000K spectrum because of the peaks in BOTH blue and red
ends of the chart.
As you move UP in CRI it puts out less light, but 90CRI “are supposed to”
speed up flowering. Read something about higher CRI closer to natural solar
but have NEVER seen a chart showing say 3000K 70-80-90 CRI in one graph.
Current story - EB strips 4000k were at 30 inches above plant while sexing.
Past runs under 3000 & 35000 the plants would stretch to 12-14 inches in
the time to show sex. This time only reached 8 inches, but the underscape
was pushing hard against the undersides of the fans to get out.
Have a second group ready to sex (different and unknown strains) and since
the heat is mostly over will turn on 3000K & 3500K 80CRI spots to see if it
influences the growth. I’ve moved the EBs down to the same height that is
used for the Veros in the past. For the last month of flower will turn on the
90CRI (with or without the 80CRI) and give it a shot for late flower.
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Wow! That’s some heady shit man. I’m grateful for you really smart guys that can cipher this shit out. I’m gonna smoke a fat one now and marvel at your genius! One Love.
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lumens are not what we want, but 80cri have more in that case (3500K).after month under my diy i see 90cri flowers better faster imo . should be best as you have written - first month 80cri and second month 90cri ,-)
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Madscientist… Can you hooked me up with a link to those lights? Doing a new build coming up, think I’m going to leave my hps and try the cri.
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The problem with 90 CRI diodes is that they are significantly less efficient that 80 or 70 CRI chips - which means less light/PAR per watt. A little “better” spectrum - in the sense of being truer to natural sunlight - but quite a bit less of it. It’s a trade-off. -b420
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This is a nice thread I’ve been away for a bit but I’m soon to be using both my LEDs again the first to fire back up is my Johnson cx-6 that has cree cxb 3070 chips , newer ones use citizen my second led is a California light works ss-275 that uses osram diodes both have worked well for me the Johnson being the more powerful of the 2 I’m gonna have to take more time to study your thread as I see a lot of good stuff here
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Are there any tutorials out there on building leds? Don’t know enough about them and whatall is needed to build a set. What would I need to replace a 1000w hps? With the heat I’m dealing with I’m betting I can get more in my room with less heat with led
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Just bumping this up…