knight mare
Well-Known Member
What about these http://www.led-cob.com/cob-led-f50
it may be rubish though.
it may be rubish though.
3500k vs 4000k vs 5000k ?
- Thread starter Trippyness
- Start date
knight mare
Well-Known Member
To be fair, I was not looking at the lm/W I was looking more at the CCT and one vivid range has a CRI of 95
Trippyness
Well-Known Member
Professor Bugbe at Utah state University who is one of the foremost experts on plant lighting has conducted tests saying that photon output is the main reason for growth and there is no propf that a higher blue spectrum increases vegitstive growth or node spacing in plants. My main goal is to get the max photon putput. Hence checking out 5000K
Trippyness
Well-Known Member
This is not a HPS thread. HPS is less efficient than COB plus delivers less PAR per watt. This is not a debate anymore. COB led is the best lighting. Currently. Less wattage same yield or same wattage more yield. Yes electricity is just a benifit. However more yield is a huge plus and less hvac and ac that hps. Anyways back on track. More photons are more growth. So let me make this sinple. Which CCT at what CRI produces the most photons per watt? Quit with the hps bullshit.
Greengenes707
Well-Known Member
I have said it a million times...pay attention to my WHOLE statement.
The main goal of a grower is to provide the maximum amount of photons while still staying within plant requirements.
Ready, set,...Google
The main goal of a grower is to provide the maximum amount of photons while still staying within plant requirements.
Ready, set,...Google
BOBBY_G
Well-Known Member
yes but why are the light sources that "bring out the colors" like cobs and 93-cri LEC beating hps across the board on yield as well?Those look just great under the high cri. That's what the high CRI is all about, produce natural realistic looking (for us) colors. That is a result from the spectrum though, and is this case a MUCH better one if you use 3000.
2700-3000k at 90CRI is what people should be using instead of being blinded by luminous efficiency and picking 80cri 3500K. Those are the ones for fat colas. Especially buying 3500k and 4000k cri 80 and adding photo red show nicely how the lum/per watt at the light source epeen race leads to idiocracy. Buy lower color temp with cri 90 and you don't have to.
Buys led roughly 17% more efficient in producing light (top bin 3500k 80 cr vs , especially blue yellow orange, and ignores the cobs with the excellent spectrum for photosynthesis with a 640-660 peak 40% higher than the 80cri. Can buy grow light, buys bay lighting instead... All some Unlucky Brians material.
More stem elongation compared to more blue light is to be expected. It's not that big of a problem as people make it out to be though. And easy to fix by adding some cooler temp, or adding xpe for more blue. If you care about the effectiveness of efficient led you barely veg in a flower space anyway. When you have to choose only one, you obviously pick the best one for the two months flowering. And add steer lighting when necesary. That's one of the major advantages of led horticulturist and professional grow light designers are a lot more interested in.
Supra wrote a good post once with some key info:
The 80cri (and higher K) are better for warming up plants though lol
Rough, but should be obvious enough for those with more than half-a-brain:
View attachment 3694615
The 3500k and up users are mainly focussing on chlorophyll b. You're all running, as many others knew already, an efficient veg light. Which yes, can grow bud too, just like mh can. And yes, plenty of margin in efficiency to beat hps with it it gpw-wise but when you design a led grow light that is not the goal... The energy saving is inherent to led, you don't have to use a sub optimal spectrum.
The whole blue for veg and red for flower didn't fall out the sky... More blue is more compact plants, depending on R:FR ratio. In combination with daylight/fullspectrum, more FR is larger and thin leaf surface, more blue is smaller but thicker leaf surface.
This is still confirmed and researched daily by photobiologists for different plant species. As I said long ago, grow led is all about steer lighting. And the high cri version offer a very solid basis instead of the higher color and lower cri versions. Besides, as you all know, red light is way more efficient for the plant....
@Rahz: remember what I said about that the quest for lum efficiency should not lead to wasting space or light... Well here you go. That max ppfd depends on the quality of light as well. High ppfd with suboptimal spectrum leads to photoinhibition much faster. As is evident in the grows from people who claim cobs bring out the colors better... and follow that up with pics of plants showing the clear signs of photoinhibition. The unusual anthocyanin production to protect the plant against all that excess far less useful green and some blue (absorping those and removing those from the reflected spetrum, hence the red/purple appearance). At the same time it causes a decrease in quantum efficiency and reduction in net photosynthesis.
Malvidin is a common anthocyanin:
Moral of the story, most here are doing led all wrong and it's time you start talking plants instead of light source efficiency. Buy 3000k 90cri instead. Or the 2700k even, no spectrum data in the specs and may be overdoing it in terms of lowering blue,
Proper color, under hps of course:
View attachment 3694639
knight mare
Well-Known Member
I would not mind trying to veg with 6500k with some UV NIR,
Trippyness
Well-Known Member
So would you say GG that 3500K is the optimal photo to plant requirements? As opposed to 4000 and 5000K?
hillbill
Well-Known Member
In flower room now I have 630nm reds, 5250k, 4500k, 3500k and 3750k diode and cob panels. The higher blues of most LEDs and cmh seem to make for colors like purples and deep blues late. Stems of some individual plants will redden where the higher k light his them but not where shaded.
Love variety I guess.
Love variety I guess.
JungleTime
Well-Known Member
I'm not GG nor have his level of experience but I would have to say that 3500k is the best all around spectrum for cobs for veg and flower.
You stay within the general plant requirements, efficiency/lumans per watt are still high enough to defend dropping from 4k-5k. You dont lose much. You only lose a real noticeable amount when dropping under 3000k, aka the 2700k.
Airwalker16
Well-Known Member
I'd honestly really like to see a side by side of cuts taken from the same mom that are exactly identical. Length, nodes, leaf size, rooted same time. One under 2700k crees & the other under 6000ks. I think that'd be the best way to really get an idea of what differences if any there are between the different CCT's.
I can't remember who, but someone's doing one with 3k& 4k with very little noticeable difference.
hillbill
Well-Known Member
Spectrum is important, just not the only important factor. The fullness of spectrum is a win for LEDs. Even if hps was more efficient, the lack of a natural spectrum would limit the full expression of a plant. Sure, the plant will "catch as catch can" and make the best use of that lacking light source but under full spectrum light it can reveal it's true nature.
Trippyness
Well-Known Member
I agree. Why 2700K?
Trippyness
Well-Known Member
Indeed, but it seems that photons matter more than spectrum acording to Prof Bugbee at Utah state.
BOBBY_G
Well-Known Member
prob for the same reason of why 6500
hopefully more distinct differences relative to say a 3500k vs a 5000k
Airwalker16
Well-Known Member
Farthest ends of the spectrums available from cree.