Led vs HPS growing

Growoolit

Well-Known Member
Yes, that's why we believe Far Red is so interesting, as it appears to drive both photosynthetic and a number of photomorphogenic responses that are complimentary. One issue is that Far Red is costly to provide in terms of LED efficiency as most 730nm LEDs we've looked at have been around 50-55% efficient, and depending on what spectrometer you use, it does not show up as PAR and therefore is not necessarily counted in umol/j numbers that encompass the traditional 400-700nm range. So it makes your lamp look less efficient compared to a more traditional LED grow light, which not everyone understands.


Certainly we believe having a "true" full spectrum is advantageous – that has always been the philosophy behind the High Light design. But efficiency is always going to come into play and not just due to "bragging rights" but because even though spectrum makes a difference to plant growth, providing more photons (up to a point) appears to make a bigger difference. Although I have often wondered if in fact having a more complete spectrum allows you to push the boundaries of maximum DLI by targetting photoreceptors more equally and not overloading some while underdriving others.

The spectra you describe above is really just a drive for greater efficiency, as the cheapest colours you can combine (in terms of LED efficiency and quantum yield) are 660nm mono and CRI70 white phosphors around 5000K. CRI80 3000K is usually thrown into the mix to balance out the orange-red end of the spectrum and does not hurt efficiency that much when mixed in moderate numbers, but I do have a little laugh to myself every time I read the words "Full Spectrum" when looking at an LED lamp that has almost no light under 440nm, almost no light over 700nm, and almost no light at 480nm. When you look at all the photosynthetic absorption peaks missed out by most LEDs, you do start to wonder. But it also shows just how adaptable plants are.
I believe that in reality " targetting photoreceptors more equally and not overloading some while underdriving others" , hardly ever happens.
This would be due to photoreceptors being produced by the plant which target and maximise energy transfer and photosynthesis in relation to the incoming light. It definitely shows how adaptable plants are, as you said above

@Grow Lights Australia I really like the path you are taking in your LED endeavor. Any change you could convince one of the owners of your boards or someone in house to grow some lettuce under your lights as an experiment to see how leafy crops respond to your current spectrum?
Is that a valid test, as lettuce is a low light user (I'm told). Maybe tobacco... but that may not be legal (in Australia).
 

hybridway2

Amare Shill
You always provide such good and detailed posts!

I did touch on solvent vs aqueous solution suspension for measuring absorbance in the THC Testing thread, so I know exactly what you are talking about, and even hypothesised a little on the subject: https://rollitup.org/t/more-thc-testing-uva-vs-uvb-vs-near-uv.1010801/page-8#post-15697300

I also found a more up-to-date study on the Emerson Effect, as it was bothering me that the original test was done with 700nm Far Red and I was wondering if there was any residual effect around that wavelength. What I found was that 720nm has the highest synergistic effect, followed by 710nm and then 730nm.

Here is the study: https://thescipub.com/pdf/10.3844/ajbbsp.2014.234.240.pdf

Here is a graph from the study
View attachment 4656121

I guess I should have chosen my words more carefully, too. Quantum Yield graphs do show a small amount of photosynthetic efficiency beyond 700nm, so it stands to reason that Far Red on its own does drive photosynthesis. But not much, and then only in combination with light harvested from PSII pigments. I was really just thinking out aloud trying to figure out what was responsible for Emerson's "Red Drop" phenomena.

In any case, we do believe Far Red is an important spectrum. Just as we believe other spectra not normally found in typical white-phospohor LEDs, such as 405nm and 480nm, are important. We are hoping to show you guys just how important we think they are in the next few weeks. :cool:
Man, do you have any idea how much we are on the same page? Kudos & I'm looking forward to it. As well as a diode protectant surface, optional diffusion would be stella but i never used your boards to know if necessary just began to believe it always is when regarding led.
Almost made the buy that day. But am waiting.
Thanks for sharing this info & pls continue!
 

Barristan Whitebeard

Well-Known Member
Is that a valid test, as lettuce is a low light user (I'm told). Maybe tobacco... but that may not be legal (in Australia).
If they're growing leafy greens such as lettuce, the person could just dim the High Light boards and/or raise them. This would enable them to maintain an acceptable PPFD/DLI for the lettuce, comparable to light levels that a cannabis grower using the High Light boards for the full growth cycle would aim for in early to mid veg.
 

Barristan Whitebeard

Well-Known Member
What do y’all think of this spectrum? This is from GE. Intended to be a direct de hps replacement. View attachment 4657003View attachment 4657004View attachment 4657008
@canope just bought two of the Arize Element L1000 and added them to his room otherwise filled with Meijiu bar lights. Type F spectrum I'm pretty sure.

 

canope

Well-Known Member

oswizzle

Well-Known Member
I bet 4 of those lights over a 4x8 tray would be sick... the Gavitas are 4x4 dimension and you cant push the limit... these are nice and slim...looks like u can really test LED potential Wattage for Wattage wise with these.... Me like
 

canope

Well-Known Member
I bet 4 of those lights over a 4x8 tray would be sick... the Gavitas are 4x4 dimension and you cant push the limit... these are nice and slim...looks like u can really test LED potential Wattage for Wattage wise with these.... Me like
I saw someone do 4 of these on a 4x8. I think it’s a bit of an overkill. I like this kind of setup that was done with Fluence Vypr:
https://www.reddit.com/r/macrogrowery/comments/i8lnl7
I would replace the Vypr with L1000
 
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