Best color temp for veg?
- Thread starter Rahz
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cityworker415
Well-Known Member
My best veg is under t5 @ 6500k Sylvania tubes.Yeah?!
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churchhaze
Well-Known Member
I use blue panels for veg and red panels for flowering.
I like growing with LED!
I like growing with LED!
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Doer
Well-Known Member
Now that's a thought.
Low-pressure sodium lamps—producing up to 180 lumens per watt—have the highest efficacy of all commercially available lighting sources. A low-pressure sodium lamp is shown in the image below.
Low-pressure sodium lamps operate much like a fluorescent lamp and require ballast. The lamps are also physically large—about 4-feet long for the 180-watt size
churchhaze
Well-Known Member
LPS also has a higher LER than HPS, which means that 180lm/W of LPS SPD is lower efficiency than a hypothetical 180lm/W of HPS SPD, assuming a lamp like that actually existed.
AquariusPanta
Well-Known Member
Good thread. We agree. No best color temp, your mileage may vary.
A vote would have been nice for the thread...(derp).
I believe 5000K wins the contest.
PSUAGRO.
Well-Known Member
Now that's a thought.
Low-pressure sodium lamps—producing up to 180 lumens per watt—have the highest efficacy of all commercially available lighting sources. A low-pressure sodium lamp is shown in the image below.
Low-pressure sodium lamps operate much like a fluorescent lamp and require ballast. The lamps are also physically large—about 4-feet long for the 180-watt size
good luck using that as your primary light source
..............someone in here wanted too, never happened?still interested to see what would come of it ..........
AquariusPanta
Well-Known Member
good luck using that as your primary light source
still interested to see what would come of it ..........
Mellow yellow light... right?
alesh
Well-Known Member
...about 500 lm/W making a 180 lm/W LPS 36% efficient (about 1.8 umol/J).
Doer
Well-Known Member
good luck using that as your primary light source
still interested to see what would come of it ..........
Doer
Well-Known Member
Just some facts as we go along. Negative CRI?
http://en.wikipedia.org/wiki/Color_rendering_index
Numerically, the highest possible CRI is 100, for a Black body (incandescent lamps are effectively blackbodies), dropping to negative values for some light sources. Low-pressure sodium lighting has negative CRI; fluorescent lights range from about 50 for the basic types, up to about 90 for the best tri-phosphor type. Typical LEDs have about 80+ CRI, while some manufacturers claim that their LEDs have achieved up to 98 CRI.[6]
http://en.wikipedia.org/wiki/Color_rendering_index
Numerically, the highest possible CRI is 100, for a Black body (incandescent lamps are effectively blackbodies), dropping to negative values for some light sources. Low-pressure sodium lighting has negative CRI; fluorescent lights range from about 50 for the basic types, up to about 90 for the best tri-phosphor type. Typical LEDs have about 80+ CRI, while some manufacturers claim that their LEDs have achieved up to 98 CRI.[6]
Doer
Well-Known Member
This is a strange thought puzzle to me.
If 100 CRI is all colors appear just like outdoors.
And LPS can be slightly negative
Then -100 CRI makes you see no color, all gray?
Or do colors swap to opposite and/or blur to the same, like in color blind?
What is the other end of the scale? What is -100 CRI?
If 100 CRI is all colors appear just like outdoors.
And LPS can be slightly negative
Then -100 CRI makes you see no color, all gray?
Or do colors swap to opposite and/or blur to the same, like in color blind?
What is the other end of the scale? What is -100 CRI?
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heckler73
Well-Known Member
I don't understand the point of CRI WRT horticulture, unless one is worried about display of flowers or photography.
Case in point, if CRI meant anything, then incandescent bulbs are the best for growing. They are genuine BBRs.
It's all about the Fermi energy levels, man...
As for negative CRI, let's try reverse engineering the equations to see what is happening.
So, if CRI = -100, that implies (on average) each Ri is -100.
Following through the math one finds each d(U,V,W) to be ~ 25.1
What does that mean?
It means when compared to a reference illuminating source, the colour of the swatch is muddy or quasi-monochromatic. I'm sure my Blurple/Rellow MC has a crappy CRI, too. (Actually, after I put in the new 5x5MC with one green LED, it looks more natural. 1 green to 49 "Blurples"
) It appears to be a long-winded calculation of residuals, in the end.
Doer
Well-Known Member
@heckler73. Math wizz!!
CRI in Horticulture is only loosely coupled to efficiency, but we see from the charts there is a
penalty to pay, there, for highest CRI.
CRI in Horticulture is only loosely coupled to efficiency, but we see from the charts there is a
penalty to pay, there, for highest CRI.
Sativied
Well-Known Member
Well that point would be true if CRI meant everything, or something so significant the rest becomes irrelevant, not just anything.
And even then CRI alone means very little without spectral distribution and ctt. CRI 98 still isn't going to produce great light and realistic colors for photography if the temp is too low for example.
It doesn't relate directly to photosynthesis efficiency but given the right light photomorphogenesis is affected and lights like the LEP as well as greenhouses turning off light (to soak up day light only for a short time) show interesting benefits. Involves plant shape, root growth, chloroplast transport, leaf arrangement, stomata openings, and many other factors that indirectly do contribute to efficiency. It's an accepted fact amongst experts that using a tuned spectrum can lead to much better plants and more product than daylight, but at the same time plants evolved under sun light and don't utilize all of their genetic potential - of which some can lead to a net higher production and/or quality - under anything else.
Not CRI specifically, old and probably posted before:
"Results from this study show that light quality and quantity affect cannabinoid synthesis in the growing plant. The effects were evident on the concentration of the principal cannabinoid component (A9-THC) of this strain..."
http://www.beckleyfoundation.org/bib/doc/crl/Cannabis_the_plant/Mahlberg_1983.pdf (remove file name to browse more docs...)
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nomofatum
Well-Known Member
6500k crushes 5000k in my experience. Depends on what you are going for though. 6000-7000k will give dense shorter bushes. 3500k will result in taller lankyer/less bushy plants. For bigger plants 5000k may be a good choice, for a fast, dense, and extremely healthy canopy 6500k is very hard to beat.
bicit
Well-Known Member
Using a finely tuned spectrum is one thing. However I'm not really that convinced that CRI plays a critical role in horticulture lighting. I mean, HPS lamps have a CRI of about 25 and are still the benchmark to be measured too. Seems like for the most part, CRI is for humans, and more isn't necessarily better.
http://www.fullspectrumsolutions.com/cri_explained.htm
http://www.fullspectrumsolutions.com/cri_explained.htm
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