DIYers try to recreate CREE vs Gravita?

[wietefras]

@wietefras have you done any testing? I'm just curious how you know.

Yes I have done plenty

Feel free to share the ultimate light recipe which you found though. I guess you know what is best right?

What's the point of saying there is a better spectrum when you don't know what that is? We know that White COBs work. We don't know if some random PCB with green leds works. So what would you go with?

 

[CobKits]

emulating sunrise/sunset is not some much an intensity but a color spectrum issue.

yes we were talking about spectrum specifically

 

[wietefras]

emulating sunrise/sunset is not some much an intensity but a color spectrum issue. Sunrise is a deep red first sun, turning to orange and then yellow as we perceive it. Sunset is a far red with a tint of blue to our perception. natural light has more invisible light we cannot see like IR and such. Most beneficial is a narrow band of reds for both but different reds. So I posted some excerpts from an led magazine from a group on another site I interact with. this same discussion is being had everywhere.

Compeletely wrong again. It's much more an intensity issue. You can easily see this in the plants.

Clarifying my statement on expertise is not meant to belittle anyone

You have no expertise at all. Copy pasting some google results is not "expertise".

This thread was nothing about finding the best spectrum. That's just your spin to deflect MeGaKiLlErMaN calling you out for posting yet more useless "advice" to buy some unknow PCB with green leds on it for christs sake.

 

[NaturalFarmer]

Compeletely wrong again. It's much more an intensity issue. You can easily see this in the plants.

Care to clarify?

 

[wietefras]

Care to clarify?

Well for one, you can clearly see how the massive difference in light intensity from sun up/down to noon affects the plants. Now try seeing the same difference with light that's a bit more red or a bit more blue. The color spectrum shift shows no difference over a single day at all.

The only way spectral differences come into play (if at all) is when you look at seasonal changes. More (far) red in autumn which will help with flowering.

The reason people use daily light curves is because of light intensity. To prevent hammering the "sleeping" plants with 100% light from the start or switch off the light from 100% to 0% at the end. Plants need to ramp up or off their processes.

I monitor just about everything of my grow and the charts show quite clearly that the plants suffer from the morning spike. They are not yet evaporating properly and thus the leaves heat up a lot. Until the evaporation is up to speed and everything normalizes. Still that's a potential source of stress every day. Same with lights out since the water is still being taken up by the roots, but then the evaporation stops.

Besides that there is a daily (circadian) rhythm in the plants itself which reflects in the charts. I can clearly see in the charts that they deal much better with the light in the middle of the day as opposed to start or end. Their evaporation is at peak level around the middle of the "day". This effect is most visible in the VPD chart which tracks plant leaf temperature, ambient temperature and relative humidity showing how "comfortable" the plant is in the current climate

This is a chart of a 12 hour "day" with a bit of dark period at the beginning and end:
.

 

[NaturalFarmer]

Well for one, you can clearly see how the massive difference in light intensity from sun up/down to noon affects the plants. Now try seeing the same difference with light that's a bit more red or a bit more blue. The color spectrum shift shows no difference over a single day at all.

The only way spectral differences come into play (if at all) is when you look at seasonal changes. More (far) red in autumn which will help with flowering.


View attachment 3908320 .

The light change isn't due to intensity but diffusion and the way blue light is filtered in the extended atmosphere during sunrise/sunset and reds are allowed to pass unobstructed. Am I missing your point?

http://www.ccfg.org.uk/conferences/downloads/P_Burgess.pdf

 

[wietefras]

The light change isn't due to intensity but diffusion and the way blue light is filtered in the extended atmosphere during sunrise/sunset and reds are allowed to pass unobstructed. Am I missing your point?

http://www.ccfg.org.uk/conferences/downloads/P_Burgess.pdf

There usually is a quite noticeable difference in light intensity between sunrise and noon. Up to 100% difference actually.

 

[NaturalFarmer]

There usually is a quite noticeable difference in light intensity between sunrise and noon. Up to 100% difference actually.

I understand but why is that? Diffusion? Horizon obstructions?

 

[sixstring2112]

atmosphere diffusion,same thing happens with the moon.when it first comes over the horizon the light from the sun/moon has to travel through much more of earths atmosphere to get to us.i would think the diy led crowd would know these simple science facts lmao.our atmosphere changes the color of the sun ya dorks!!!

 

[MeGaKiLlErMaN]

atmosphere diffusion,same thing happens with the moon.when it first comes over the horizon the light from the sun/moon has to travel through much more of earths atmosphere to get to us.i would think the diy led crowd would know these simple science facts lmao.our atmosphere changes the color of the sun ya dorks!!!
View attachment 3908394

Yeah this is known, but the summer sun at noon-4pm is what I'm looking for for spectrum.

 

[NaturalFarmer]

Yeah this is known, but the summer sun at noon-4pm is what I'm looking for for spectrum.

 

[MeGaKiLlErMaN]

View attachment 3908455 View attachment 3908456 View attachment 3908457

Nice, good to see its around 2000ppfd that means I can hit that target with some decent cobs.

 

[CobKits]

2000 ppfd with targeted spectrum cobs is too much. remember that 2000 ppfd sunlight contains a shitload of green the plants are reflecting. 1500 ppfd prob better target for aggressive growth with cobs. also remember the sun is only hitting 2000 for an hour or two, not pounding 12hrs worth

 

[NaturalFarmer]

2000 ppfd with targeted spectrum cobs is too much. remember that 2000 ppfd sunlight contains a shitload of green the plants are reflecting. 1500 ppfd prob better target for aggressive growth with cobs. also remember the sun is only hitting 2000 for an hour or two, not pounding 12hrs worth

Curios how much would you say this would change with supplementation of CO2 at 1500ppm? Do you think you could push 2000ppfd with it? Or is that just in relation to heat and not photons?

 

[sixstring2112]

1500ppfd and no co2 cept my bad breath haha.

 

[sixstring2112]

Yeah this is known, but the summer sun at noon-4pm is what I'm looking for for spectrum.

Summer at noon where? And what time of year? Its pretty much be concluded that the average ppfd of the sun on a clear day is around 2000 oooooooomoles.but its such a bad example of what we would expect indoors with artificial lighting.we have targeted spectrums we all use.the sun is just such a broader spectrum it would be foolish to chase the numbers.indoor is more constant like coberto said but not just lighting,temps,rh wind speed is all controlled indoors.alot of info already exists on indoor pot farming.1000ppfd is awesome 1500 and co2 is awesome.fuck man i got plants under 600ppfd lookin bomb as hell right now.my new section is bangin 1500 at the canopy and im chasin my tail to keep the plants watered enough and fed right.good luck at 2000,every aspect of the grow will need to be 110% or things will go south imo.but hey we wont know if someone doesn't set it up and try it.i think 1 quantum board per sq foot @ 100w per board will achieve 2000ppfd or close in a 10 x 10 area it would be sick.there goes efficiency lol.

 

[NaturalFarmer]

Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550641/pdf/12298_2008_Article_27.pdf

 

[CobKits]

1500ppfd and no co2 cept my bad breath haha

and your massive airflow that keeps em breathing

good luck at 2000,every aspect of the grow will need to be 110% or things will go south imo

1500 is hard to master even

 

[CobKits]

i think 1 quantum board per sq foot @ 100w per board will achieve 2000ppfd or close in a 10 x 10 area it would be sick.there goes efficiency lol.

with enough height above canopy you can grow truly outdoor size with a rig like that. your 700 and 1050 mA cob rigs arent far from that in efficiency. youd be like 4 cobs/SF

 

[Rahz]

Diminishing returns increases at any two points in a PPFD chart. People need to examine whether it's worth the extra juice to squeeze out a few more grams. My experience with sub 800 PPFD has been very good, on the order of 55-60 g/ft. Bumping the levels up to 1000 doesn't present a challenge to the plants but going over 1300 can begin to be problematic. The yield difference between 1300 and 1500 is likely negligible even under ideal circumstances. People have recently been planning 1800 and 2000+ PPFDs. I don't see the point from a practical perspective but there's useful field data to be had on the order of "this is why you don't do this". I say bring it on... but I wouldn't recommend it. My ideal system would be capable of 1200-1300 PPFD with the ability to dim. I would be happy with 1000 PPFD, something I never even grew with.