Max PPF/PPFD with and without Co2

[MeGaKiLlErMaN]

@MeGaKiLlErMaN, True, but for instance that 1000W might also put 850PPFD on the plants in my room if I have better reflective walls. So it doesn't say much about the 1000W light. Also it might be cheaper to invest in a bit of reflective material than buying whole new lights.

Yes but my measurements show that that isn't possible with a DE HPS or normal HPS. Even with reflective walls.. Mine were not the most reflective but still.

 

[wietefras]

And then there is a matrix that shows at least an average 800 PPFD with that light.

Anyway, that wasn't my point, but never mind.

 

[MeGaKiLlErMaN]

And then there is a matrix that shows at least an average 800 PPFD with that light.

Anyway, that wasn't my point, but never mind.

Can you post it? I would like to see the layout of the lights to see how the measurements add up, so I can further support my theory or disprove it.

 

[Shugglet]

These threads are sooooo fucking pointless... but I do like em lol.

 

[Shugglet]

That "Chandra" chart has always been a bit suspect. All in all it's pretty much like any light response curve, but it seems a bit too steep. People who tried different light intensities (including myself) did not see the exponential gains in yield/Watt which you would expect from that chart when lowering the light levels. In reality the relation between light intensity seemed much more linear between 400umol/s/m2 and 1000umol/s/m2.

A couple of years ago on the YOR (Yield-O-Rama) site they were looking into which factors attributed most to increased yields. For this they collected a lot of yield information from many growers. In total something like 175 grow reports were submitted.

I plotted those results in a chart showing the yield in g/m2 on the vertical axis and estimated light intensity in umol/s/m2 on the horizontal axis. The red line is a smoothed average. Blue points are without CO2 and green with CO2.

View attachment 3788419
This is based on grow reports with different genetics, different lights, different temperatures, different medium (hydro/soil), different stock (cuttings vs seeds) etc etc etc. Yet on average it looks pretty much like the chart we have all been using and it shows that adding more light well over 1000umol/s/m2 still increases yield. Only above 1500 umol/s/m2 does it really seem to taper off, but there is not enough data there to say anything definitive.

Still, the biggest difference compared to the "Chandra" chart, is that it indeed shows a much more linear slope between 400 and 1000 umol/s/m2 range.Based on the average line you could expect an average yield of 0.56g/umol/s/m2 @ 400umol/s/m2 and 0.48g/g/umol/s/m2 @ 800umol/s/m2. That would make it around 15% less efficient to run with 800PPFD instead of 400PPFD, but you would also get 70% more yield from the same space. Most likely more compact and harder buds too under the higher light intensity. So less grows needed for a certain amount, more yield from the same area and better (higher priced) product overall. That's why people tend to average around the 600 to 800umol range instead of 400.

It also demonstrates another major mistake in FUD's reasoning that the "optimal" value would be the saturation point. This chart indicates the average saturation point for cannabis is around 1500umol/s/m2. Yet virtually no one is growing at this "optimal" value. Or the other way around, even if the saturation point was around 400umol, it would be much more efficient to grow at 200umol/s/m2.

:edit: Added distinction between CO2 enrichment and no CO2

Considering all the variables present, why not focus on the "best" results to more accurately find an "optimal" line? Its not like its going to change the integrity of the results that much, as it didnt have a whole lot to begin with.

 

[PhotonFUD]

That "Chandra" chart has always been a bit suspect. All in all it's pretty much like any light response curve, but it seems a bit too steep. People who tried different light intensities (including myself) did not see the exponential gains in yield/Watt which you would expect from that chart when lowering the light levels. In reality the relation between light intensity seemed much more linear between 400umol/s/m2 and 1000umol/s/m2.

A couple of years ago on the YOR (Yield-O-Rama) site they were looking into which factors attributed most to increased yields. For this they collected a lot of yield information from many growers. In total something like 175 grow reports were submitted.

I plotted those results in a chart showing the yield in g/m2 on the vertical axis and estimated light intensity in umol/s/m2 on the horizontal axis. The red line is a smoothed average. Blue points are without CO2 and green with CO2.

View attachment 3788419
This is based on grow reports with different genetics, different lights, different temperatures, different medium (hydro/soil), different stock (cuttings vs seeds) etc etc etc. Yet on average it looks pretty much like the chart we have all been using and it shows that adding more light well over 1000umol/s/m2 still increases yield. Only above 1500 umol/s/m2 does it really seem to taper off, but there is not enough data there to say anything definitive.

Still, the biggest difference compared to the "Chandra" chart, is that it indeed shows a much more linear slope between 400 and 1000 umol/s/m2 range.Based on the average line you could expect an average yield of 0.56g/umol/s/m2 @ 400umol/s/m2 and 0.48g/g/umol/s/m2 @ 800umol/s/m2. That would make it around 15% less efficient to run with 800PPFD instead of 400PPFD, but you would also get 70% more yield from the same space. Most likely more compact and harder buds too under the higher light intensity. So less grows needed for a certain amount, more yield from the same area and better (higher priced) product overall. That's why people tend to average around the 600 to 800umol range instead of 400.

It also demonstrates another major mistake in FUD's reasoning that the "optimal" value would be the saturation point. This chart indicates the average saturation point for cannabis is around 1500umol/s/m2. Yet virtually no one is growing at this "optimal" value. Or the other way around, even if the saturation point was around 400umol, it would be much more efficient to grow at 200umol/s/m2.

:edit: Added distinction between CO2 enrichment and no CO2

Awesome stuff!


This actually supports my position, which I am not really surprised about.

"Based on the average line you could expect an average yield of 0.56g/umol/s/m2 @ 400umol/s/m2 and 0.48g/g/umol/s/m2 @ 800umol/s/m2. That would make it around 15% less efficient to run with 800PPFD instead of 400PPFD"

The remainder of the statement, "but you would also get 70% more yield from the same space." it incorrectly referenced, it should be area. Since we are compare two different light intensities over two different coverage areas, I am indeed correct.

Remember, I am saying ~400-600 umoles to 80% (or more) is better than >1000 umoles to the top 20%.

The rest of your conclusions are self refuting so I won't waste the time explaining.

 

[PhotonFUD]

It's not a case of "more important", but of different applications. You use PPF to compare lights and you use PPFD to measure how much light the plants are getting in your own grow room.

PPF doesn't depend on anything. It's a measure of total light output and can therefore be uses as an objective measure comparing lights
PPFD depends on a ton of things in your grow room and cannot be use for comparing

In the end PPFD is what counts for the plants, but when you want to see which light is most efficient you need to look at PPF. Basically you divide PPF by the surface area after deducting wall losses.

Those people who "beat" HPS lights tend to do so by getting only 0.5g/W under the HPS. That's like running against a sprinter with a broken leg and claiming you beat a gold medal champion.

You finally came around. *clap* *clap*

Progress.

 

[mauricem00]

These threads are sooooo fucking pointless... but I do like em lol.

they are not pointless. they give bored lonely stoners something entertaining to do. this discussion reminds me of something a gardener at the university told me many years ago," I don't understand all these fancy theories these kids are telling me. I need to listen to my plants and let them tell me what they want" those kids had entertaining theories but that gardener had some really nice trees and flowers. I think maybe he knew more about growing plants than those professors who were teaching those fancy theories.

 

[PSUAGRO.]

they are not pointless. they give bored lonely stoners something entertaining to do. this discussion reminds me of something a gardener at the university told me many years ago," I don't understand all these fancy theories these kids are telling me. I need to listen to my plants and let them tell me what they want" those kids had entertaining theories but that gardener had some really nice trees and flowers. I think maybe he knew more about growing plants than those professors who were teaching those fancy theories.

A farmer that grows/harvests the same species yearly will always know more about that crop than some book/class knowledge , I know this first hand, got put in my place many times out of school==== YES , experience matters.......duh

they run their hands through the dirt and i'm suggesting a soil test..........the stares I got where priceless,lol

 

[MeGaKiLlErMaN]

And then there is a matrix that shows at least an average 800 PPFD with that light.

Anyway, that wasn't my point, but never mind.

Everything I have found states that this is the optimal setup, (you want it at the middle of the curve to allow for a large amount of plants) But Im just not seeing that same graph that you used, or figuring out how it associated the 10 and 20 on the graph.. Unless that was consumption per umol/M^2? Anyways just currious of the layout that you talked about earlier and the graph info.
Thanks

 

[wietefras]

@MeGaKiLlErMaN, I was talking about lights not CO2.

 

[MeGaKiLlErMaN]

@MeGaKiLlErMaN, I was talking about lights not CO2.

yeah thats what Im talking about, and asking. How was the consumption of CO2 being demonstrated.. it looked like it had a 10 and a 20.. so I guessed that it was per meter^2. Can you confirm or elaborate?

 

[CobKits]

Everything I have found states that this is the optimal setup, (you want it at the middle of the curve to allow for a large amount of plants) But Im just not seeing that same graph that you used, or figuring out how it associated the 10 and 20 on the graph.. Unless that was consumption per umol/M^2? Anyways just currious of the layout that you talked about earlier and the graph info.
Thanks

is this graph from 1940? were over 400 ppm atmospheric right now

 

[MeGaKiLlErMaN]

is this graph from 1940? were over 400 ppm atmospheric right now

Its the only one I could find! lol I want accurate info but if Im not 100% sure how to read it what good is it?

 

[CobKits]

it might be from 1940, nothing wrong with that!

 

[PhotonFUD]

it might be from 1940, nothing wrong with that!

Depends on where the reading was taken. Higher elevations may have less CO2 than lower ones, to what degree I do not know.

I do know that the average C02 PPM level for our atmosphere is pegged around ~400. There is a research station in the far north that has been measuring for a while (decades) and it has been steadily increasing, albeit at a slow rate.

Go into a city and things significantly change. Even time of day.

 

[Hybridway]

Answer to the question or statement in the heading, max PPF/D w/ Co2 is 1300-1750 strain dependent. On average in regards to MJ. Sure, there's the matter of efficiency. Same w/ cobs n all that shit. Efficiency is way overrated when growing pot. Max yields is the goal. Max, because no loss of money or material used to harvest max is ever not worth sacrificing in comparison to the value of the product. Not the topic.
Anyways, why not focus on the saturation points of cannabis & saturation points of Co2. Once you've found both then you there have your max. Just my opinion. Nothing as in depth of youz guys conversation. Just 2 cents!

 

[Megalomando]

Hi! Some clarification if you would.

I'



I've seen mention of up to 65 mol/d and according to purdue university studies on different plant species, most other light loving plants like sunflowers and tomatoes are recommended for a DLI between 22 and 30mol/day.



So for cannabis, bottom threshold for optimal growth and photosynthesis is a DLI of DLI of 22 would be:
24/0 schedule: 254.6 micromoles/m2/s-1
18/6 schedule: 339.5 micromoles/m2/s-1
12/12 schedule: 509.25 micromoles/m2/s-1


For Cannabis, the Top threshold for optimal growth and photosynthesis is a DLI of 65 moles per day.
***extremely important notice, only go up to these amounts if you are using supplemental CO2, do not go this high if you are not using supplemental CO2 as you will actually slow down photosynthesis and waste energy.

24/0 schedule: 752.31 micromoles/m2/s-1
18/6 schedule: 1003.08 micromoles/m2/s-1
12/12 schedule: 1504.6 micromoles/m2/s-1


The generally accepted guidelines for artificial light PPFD in flowering are this:
in a 12/12

PPFD of at least 510 micromoles/m2/s-1 for the low end of optimal intensity
PPFD of at least 800-1100 micromoles/m2/s-1 for perfect optimal lighting without additional CO2.
PPFD of at least 800-1500 micromoles/m2/s-1 for perfect optimal lighting WITH additional CO2.

I recently obtained an Apogee MQ-500 PAR meter with the upgraded sensor so I can finally get real answers regarding PAR and where to best place the plants/lights. I take the above to understand a PAR reading of 800-1100 is ideal for 12/12 bloom, with no added CO2. With this, I'll keep the upper limit a little under 1100.

I'm not sure what the PAR reading should be for Veg under 24/0 or 18/6, any suggestions?

Thanks!

 

[CobKits]

Easy answer, It will always help... but its not really needed till youre pushing way more light than we currently do... The drop off on this chart is where you need CO2. Supplementation will never hurt... but its not always as cost effective as people think. Even shorter answer... after 1500PPFD at 86F... good luck hitting that lol

View attachment 3788162

i always wonder if that chart specs leaf temp or ambient (prob ambient, and if so, what kind of light and leaf temp rise does it assume)

who knows the OG source article?

 

[CobKits]

Efficiency is way overrated when growing pot. Max yields is the goal.

id put quality above yield but that was prob a given in hybridland...