Grams-Per-Watt is an erroneous measure of productivity

[StealthyStalks]

OP:

One more thought, please poke holes in it if you see any:

The most ideal method would probably be using PPFD weighted to Quantum Yield (QY). Then replace the kWh datum that QY datum because it's much more accurate to compare grows or evaluate grows (energy/time/yield) with photons plants use (PPFD) verses the kWh used by the lamp+ballast (where much of the energy is lost as non-PPFD quanta and heat). But, to use QY one needs at least a quantum senor, data logger and good math skills, so using kWh is the most feasible, if not the most ideal.

You are abosolutly correct! I just don't have a way of measuring flux density so it would be beyond my means. Again, good info!

Up the rep...

 

[Okiedope]

I well I found some light bulb paint. I am going to paint some bulbs red and some blue so I can hit the exact spectrum for plant growth!

be sure to buy 4 cans of red to every 1 can of blue for the correct ratio. good luck, can't wait to see the grow.

 

[secondtry]

OP:

Thanks. I noticed I made a typo as "energy/time/yield" when your original quotation was "energy/time/days"; my bad, sorry. And again, I commend you on this thread, and your ability to "stay above the fray"

 

[IWanaGetHiSoHi]

I use a Scooby Doo night light and a blue Lava Lamp in veg. I add 2 red Lava Lamps for flower ... HIDs LEDs and Floros are Highly Over Rated

 

[suckerrepellent]

My last harvest was 2072 dry grams but only 8 days of veg from clone and 9 bloom weeks. Strain matters a lot here I think. I can flower early and get solid yield in less time, but way more plants (36) than you probably.

For awhile I thought gpw was the "holy grail" but now I just try to outdo my last crop. If I can't then I did something wrong or different that hurt yield and I take a note of it and change it next round. Im always striving to get better, not hit some subjective goal.

please don't look at this like an attack. I respectfully disagree. Following i will explain how this statistic is improperly applied (as you are doing here) and is far from irrelevant or erroneous.

maybe you can clear this statement up for me.
It is true, a static gram per watt table is useless, as you said its dependent on genetics, environment and grower experience. therefore comparing the gram per watt output of OG kush to trainwreck, or sour diesel to bubblegum is an erroneous statistic as a blanket guide for growers, you will not get the grams per watt on some variety you get on others. but what you are not considering, is that there is no difference between what you described, and measuring your production on a gram to watt level. as you said, you are constantly trying to increase your yield, which is nothing more than trying to raise your gram per watt level. just because you choose to ignore the statistic, doesn't make it a bad measurement as far as comparing your OWN results run after run. rather than dividing your XXXX gram yield per watt, your are simply dividing your XXXX gram yield PER LIGHT. just cause you call it XXXX grams per 1000 watts, doesnt reflect any sort of different statistic as far as i am concerned. you are treating it like a reflection of the growers skill, and while this is true to some degree (for instance, improving his yield without diminished quality), but a generalization of say Xg/w or your not a good grower is indeed ridiculous.

so a recap, using yield per harvest is the exact same thing as grams per watt. as long as you aren't changing the factors you control (wattage, strain, nutes, soil, SQ feet of canopy), the equation just uses a different name. Using grams per YEAR is a reflection of your plant count, the more plants you have the shorter the veg time, and will therefore finish more crops per year. so your harvest size improved from the last run to this one? well if your using the same strains, without altering the wattage or canopy area, guess what, your improving your gram/watt ratio as well. the reason it is percieved as an erroneous statistic is because people are applying it incorrectly, to different strains, in different grow environments like its a scale applicable to variances in the aforementioned factors. A low yielding variety isn't graded on the same weight scale as a commercial strain, so stop using the gram per watt measurement to do so. Apply it correctly, use it as a judge of YOUR mastery of the variety, use an increasing grams/per watt WITHOUT a loss in quality as a sign that you are getting more skilled and dialed in on that strain individually.

SR

 

[LEDDeveloper]

OP:

One more thought, please poke holes in it if you see any:

The most ideal method would probably be using PPFD weighted to Quantum Yield (QY). Then replace the kWh datum that QY datum because it's much more accurate to compare grows or evaluate grows (energy/time/yield) with photons plants use (PPFD) verses the kWh used by the lamp+ballast (where much of the energy is lost as non-PPFD quanta and heat). But, to use QY one needs at least a quantum senor, data logger and good math skills, so using kWh is the most feasible, if not the most ideal.

Oh, you could get a quantum sensor for relatively cheap, now days.

But to get *really* specific, you'd need to measure what actually makes it to the leaves for photosynthesis, at every square millimeter. Have fun counting that microeinstein level!

I must concur, GPW is way too ambiguous. GPWH is by far the more appropriate measurement, although again this really only works out if you're using spectrum-specific lighting. If you use any lighting that outputs unusable wavelengths of light, you're likely not going to get a realistic measurement of performance. This would apply to *most* fluorescent tubes (they do make primary-color tubes,) all HID lamps, all incandescent lamps, and even LED panels (if they use anything other than red and blue.)

But doing all that math gives even me a headache, even though it's my job! I prefer to just do a plain-jane GPWH. No specifics, no other nitpicky stuff. How much power used, how much usable material have I produced - that's what I care about. It's what we should all care about if we wish to colonize places other than the surface of the earth, say under the ocean, or out on the moon?

 

[StealthyStalks]

be sure to buy 4 cans of red to every 1 can of blue for the correct ratio. good luck, can't wait to see the grow.

Good point! It's always nice to see a grower helping another grower out. I'll be pulling up a chair to watch his grow also, could be interesting.

 

[Bud Spleefman]

I never thought of grams per KW, but it sort of fits with my way of measuring productivity.

First, what is a rooted clone? For some it's a 2 inch tall cutting that has roots. For me, it's an 8 inch tall baby plant with a bush of roots about 10 inches long, rooted in my Ez-Cloner. So, right off the bat, the guy using the Ez-Cloner has an advantage.

My formula:
Grams per watt per days off the mother... so, if you get a gram per watt in 90 days (60 days flower, 15 days clone, 15 days veg, you're getting .0111 grams per watt per day. Even this is somewhat nebulous at best, since I clone and veg under a 175 watt halide, while I flower under a 1000 hps... not sure how to account for the lower watt 175....
(and before anyone asks, yes, the halide is about four feet above the cloner to start with, and then as they root it gets slowly lowered....)

Anyway, my 2 cents... all formulas should account for the clone and veg stage, to really determine who's setup is the most productive.

 

[StealthyStalks]

I never thought of grams per KW, but it sort of fits with my way of measuring productivity.

First, what is a rooted clone? For some it's a 2 inch tall cutting that has roots. For me, it's an 8 inch tall baby plant with a bush of roots about 10 inches long, rooted in my Ez-Cloner. So, right off the bat, the guy using the Ez-Cloner has an advantage.

My formula:
Grams per watt per days off the mother... so, if you get a gram per watt in 90 days (60 days flower, 15 days clone, 15 days veg, you're getting .0111 grams per watt per day. Even this is somewhat nebulous at best, since I clone and veg under a 175 watt halide, while I flower under a 1000 hps... not sure how to account for the lower watt 175....
(and before anyone asks, yes, the halide is about four feet above the cloner to start with, and then as they root it gets slowly lowered....)

Anyway, my 2 cents... all formulas should account for the clone and veg stage, to really determine who's setup is the most productive.

Read back through the comments and you will see it's all been covered.

 

[secondtry]

Oh, you could get a quantum sensor for relatively cheap, now days.

Not good ones, the least 'good' model I will use is the LiCoir line-sensor with a data logger = > $1,000 (and the non-line quantum sensor) Then one needs math skills and ASP (Action Spectra of Photosynthesis or PA IIRC) to weigh each photon (quanta) on each nanometer to the equivalent photosynthetic effect of each photon per each nanomter. That is why I say one needs good math skills

But to get *really* specific, you'd need to measure what actually makes it to the leaves for photosynthesis, at every square millimeter. Have fun counting that microeinstein level!

No you don't, you need PPFD (photosynthetic photon flux density) which is mol/m^2/second; it is what you are describing but it's mol/m^2/time, what you describe is simply mol/area; we need mol/area/time. This is standard scientific quatitation of photons for higher plants. But to get more complicated, PPFD is only 2D (measures incident energy at leaf) and for accurate measurements of photons we need 3D (intracanopoy), i.e. PPFD-I which can be weighed with QY. To find QY of cannabis one should use "reflectance spectroscopy"; or just use ASP for higher plants (which is already available and very close to the ASP for cannabis) because a cheap "reflectance spectroscopy" setup (spectroradiometer, etc) from OceanOptics is ~$10,000.

I must concur, GPW is way too ambiguous. GPWH is by far the more appropriate measurement, although again this really only works out if you're using spectrum-specific lighting. If you use any lighting that outputs unusable wavelengths of light, you're likely not going to get a realistic measurement of performance.

That is why I suggested using PPFD in the first place...

This would apply to *most* fluorescent tubes (they do make primary-color tubes,) all HID lamps, all incandescent lamps, and even LED panels (if they use anything other than red and blue.)

It applies to *all* lamps used to grow plants, they all emit PAR (Photosynthetically Active Radiation), it's that simple. And PAR is the nanometer range (400-700) of photons which is quantified with PPFD.

But doing all that math gives even me a headache, even though it's my job! I prefer to just do a plain-jane GPWH. No specifics, no other nitpicky stuff. How much power used, how much usable material have I produced - that's what I care about. It's what we should all care about if we wish to colonize places other than the surface of the earth, say under the ocean, or out on the moon?

It's important to note what I already wrote: you would *need* to use wattage as lamp+ballast (i.e. system wattage) to normalize the datum of yield if comparing grows with people because the ballast effects the output of the lamp in PPFD (intensity) and SPD (nanomters).

 

[suckerrepellent]

mass edit, game, set, match.

If starting with identical clones and ending with identical product, how else is one going to measure their mastery/method other than G/KWH? How would you do it?

HAHAHA certainly not like this. care to explain how the same strain has a flower time of 23 days less? HAHAHA, sucks to be one of the people that agrees with you.

I have only been a member for a month or so

If two growers growing the same clone and both using a 600w HPS get 600 grams from their harvest... if the first grower did it in 60 days and the second in 83 days, it's obvious who the most productive grower is.

Grower one would have a productivity level of 1.388 grams-per-kilowatt hour: 600 grams divided by .6x12x60.

Grower two would have a productivity level of 1 gram-per kilowatt hour: 600 grams divided by .6x12x83.

The above example just used the 12/12 cycle for simplicity and to give you an idea of what I'm talking about.

HMM, where did those 23 days go if its just 12/12 cycle?? please, enlighten us as to how you magically cut three weeks from a strains flower time h:

I see what you are saying, but in my comments I do clarify things a bit.

oh, please do clarify

I didn't see the need for it though because I thought people would intuitively get it once they understood the basic concept. I'm wrong again.

the basic concept, alter a strains flowering time, reduce its natural chemical process and BAM, high gpkwh.

Don't sell yourself short, I know a high functioning individual when I see one.

haha, high and functioning more like it.

 

[StealthyStalks]

Not good ones, the least 'good' model I will use is the LiCoir line-sensor with a data logger = > $1,000 Then one needs math skills and PAS (Plant Action Spectra) to weight each photon on each nanometer to the equipment photosynthetic response of each photons per each nanometer. That is why I say one needs good math skills



No you don't, you need PPFD (photosynthetic photon flux density) which is mol/m^2/second; it is what you are describing but it's m^2/time, what you describe is simply mol/area; we need mol/area/time. This is standard scientific quatitaiton of photons for higher plants. But to get more complicated, PPFD is only 2D (measures incident energy at leaf) and for accurate measurements of photons we need 3D (intracanopoy), i.e. PPFD-I which can be weighed with QY. To find QY of cannabis one should use "reflectance spectroscopy"; or just use PAS already available because a cheap "reflectance spectroscopy" setup (spectroradiometer, etc) from OceanOptics is ~$10,000.




That is why I suggested using PPFD in the first place...




It applies to *all* lamps, they all emit PAR (Photosynethically Active Radion), it's that simple. And PAR is the nanometer range (400-700) which is quantified with PPFD.




It's important to note what I already wrote: you would *need* to use wattage as lamp+ballast (i.e. system wattage) to normalize the datum of yield if comparing grows with people because the ballast effects the output of the lamp in PPFD (intensity) and SPD (nanomters).

Anyone want to argue with this guy?

I suspect he may just have a formal science background.

 

[StealthyStalks]

again, wrong application of grams/watt. grams per watt is not designed to measure your production over the course of a year, and it does not take into account your plant count, which is what the example you gave above is completely dependent on (since nobody would suggest this statistic for comparison if the varieties were different). either these two growers are using different plant counts, or different varieties (since this statement would be senseless in the first place if the environments aren't identical)
It is very clear, more plants equals less veg time. but grams per watt is not measuring this statistic. comparing long term production between indoor grows that effectively fill their canopy between someone who grows giants and the year long bonus of having fit an additional run in is also a completely different measurement of production. im guessing since this is in the hydro forum you are comparing yields/time to soil. anyone who knows anything knows that hydro finishes faster, the uptake of all elements below the container line is accelerated dramitcally. why you would apply a set gram per watt comparison to anything but identical grow to identical grow doesn't make any sense in the first place.

your measurement is purely a function of the method. measuring grams per watt is designed to asses mastery of a particular variety, under certain circumstance. since not everyone is going for grams in a year, this thread title is incorrect, because grams per watt isnt a reflection of plant count, or veg speed, nor is it a tool for comparing different varieties to one another as if they were the same.

I have no idea what you are talking about there. Maybe I should redo the original post to clarify things I clarified in my comments. I didn't see the need for it though because I thought people would intuitively get it once they understood the basic concept. I'm wrong again.

 

[secondtry]

This would apply to *most* fluorescent tubes (they do make primary-color tubes,) all HID lamps, all incandescent lamps, and even LED panels (if they use anything other than red and blue.)

FWIW:
Green light (500-600nm) is proving to drive photosynthesis more then red light (600-700nm) under bright white light, i.e. an HID.

I am very educated in plant photosystems, photochemical reactions and quantum physics of light (Dr. Sanjay Yoshi was one of my mentors for a short time); and without starting a huge fight I must say LEDs are a *total* non-starter as a single light source. I won't get into an argument about this, I can offer plenty of facts about quantum physics showing why LEDs are inferior to HID but that's for a different thread/time. For now I will say thus: The whole PAR range is important, as is UV-b and UV-c for cannabis to produce peak levels of secondary metabolites like THC-A, CBD-A, etc. I hope you can see the problem with using LEDs as (at least) two fold: 1) not enough PPFD (ideal for cannabis is 1,300-1,500); 2) and not enough nanometers within PAR and UV-b/UV-c are represented, i.e. most LEDs are single or only a few nanometers in blue and red....and that's lame. NASA has it all wrong, they are trying to limit energy used to grow plants, not grow the best plants.

I hope that ends the hype, lies and fad of LEDs...

 

[suckerrepellent]

mass edit, game, set, match.

If starting with identical clones and ending with identical product, how else is one going to measure their mastery/method other than G/KWH? How would you do it?

HAHAHA certainly not like this. care to explain how the same strain has a flower time of 23 days less? HAHAHA, sucks to be one of the people that agrees with you.

I have only been a member for a month or so

If two growers growing the same clone and both using a 600w HPS get 600 grams from their harvest... if the first grower did it in 60 days and the second in 83 days, it's obvious who the most productive grower is.

Grower one would have a productivity level of 1.388 grams-per-kilowatt hour: 600 grams divided by .6x12x60.

Grower two would have a productivity level of 1 gram-per kilowatt hour: 600 grams divided by .6x12x83.

The above example just used the 12/12 cycle for simplicity and to give you an idea of what I'm talking about.

HMM, where did those 23 days go if its just 12/12 cycle?? please, enlighten us as to how you magically cut three weeks from a strains flower time h:

I see what you are saying, but in my comments I do clarify things a bit.

oh, please do clarify

I didn't see the need for it though because I thought people would intuitively get it once they understood the basic concept. I'm wrong again.

the basic concept, alter a strains flowering time, reduce its natural chemical process and BAM, high gpkwh.

Don't sell yourself short, I know a high functioning individual when I see one.

haha, high and functioning more like it.

 

[DrBudGreengenes]

Heres a crazy idea
"Grams of Trichomes" per KWH used
Piss on Veg Matter/Budz
Thats Compost
What Matters is the Trich's
if yur Measurin yur Dik

By GPW
You have tread upon the wrong path
​

 

[StealthyStalks]

FWIW:
Green light (500-600nm) is proving to drive photosynthesis more then red light (600-700nm) under bright white light, i.e. an HID.

I am very educated in plant photosystems, photochemical reactions and quantum physics of light (Dr. Sanjay Joshi is one of my mentors); and without starting a huge fight I must say LEDs are a *total* non-starter as a single light source. I won't get into an argument about this, I can offer plenty of facts about quantum physics showing why LEDs are inferior to HID but that's for a different thread/time. For now I will say thus: The whole PAR range is important, as is UV-b and UV-c for cannabis to produce peak levels of secondary metabolites like THC-A, CBD-A, etc. I hope you can see the problem with using LEDs as (at least) two fold: 1) not enough PPFD (ideal for cannabis is 1,300-1,500); 2) and not enough nanometers within PAR and UV-b/UV-c are represented, i.e. most LEDs are single or only a few nanometers in blue and red....and that's lame. NASA has it all wrong, they are trying to limit energy used to grow plants, not grow the best plants.

I hope that ends the hype, lies and fad of LEDs...

This dude is my hero.

When I first put this post up, I was afraid all the LED nutjobs were going to come out of the woodwork because LED's do have a pretty good G/KWH return if the plants are kept extremely short. But the quality of product that comes from LED's is woefully subpar and quality needs to be a constant when comparing.

You need to start a thread on this, secondtry!

 

[secondtry]

I suspect he may just have a formal science background.

Nope, self-taught quantum physics and all other areas of science in which I am well versed. I was able to do so by spending LOTS of time reading academic white papers, other sources and lucky enough to be mentored by Dr. Sanjay Yoshi for a short time

 

[StealthyStalks]

I understand the concept, you make a great argument for what you are saying. my point is, the gram to watt measurement is not an all inclusive PRODUCTION statistic, which is more of what yours is. your title is grams per watt is an erroneous measure of productivity, which i agree with. my point is you are drawing on production values that involve non flower period durations, applying a scale of yield as a norm across all varieties, and measuring the effectiveness of different techniques. your right, grams/watt isnt a good statistic of long term production, or a cost to profit comparison, but that is not what that is meant to represent.

gram/watt is a one time measurement, having nothing to do with the number of veg hours, or the profit margin/cost per gram. for some reason you think gram/watt reflects this, and is an invalid measurement of the economical aspect of "production" (which is correct), when realistically your argument reflects your veg time and profit margin. since you are suggesting both yield the exact same, then your comparison is cost/return of small plants or a faster medium to large plants or a slower medium (grams/kwh is obviously influenced by these), not the relative use of the gram/watt measurement as it pertains to total yield from the flower period, when comparing one growers mastery of a variety, and its desired growth variables. either that or it was a roundabout way of saying varieties with shorter flower times are more economically viable for the commercial producer.

I see what you are saying, but in my comments I do clarify things a bit.

If you don't include the energy inputs that are dictated by geographical location to keep the grow room at your baseline Temp/Humidity and are using identical clones, then all you have left is the Kilowatt hours used to see what is the most efficient method to go from clone cutting to harvest. Method could be anything: flood cycles, veg time, plant density, nutrients, reflective hoods, PH, growing media, talking to your plants, etc, etc.

 

[pedrodepaco]

I think when most people talk about gpw atleast the seed companies they mean sea of green. No veg to 1 week veg. as tight as you can pack them kind of like the m2 ratio. Basicaly you can get away from the veg by adding more plants. I think gpw is a great way for growers to mark progress. gpw per killowat hour is getting pretty deep.