I am just going to go with grams per watt… easy and a good running metric for myself to compete with myself
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right you need a photon counter they ain’t cheap. Now here’s where things are going to get funky. What we are really doing is attempting to replicate each other’s growing variables. That means… you can grow exactly like me and get exactly what I get or I can grow like you and get exactly what you get. Or…we can find that someone’s results don’t get peer reviewed and you are called a fraud 
Calling it a dick measuring contest was actually way off base. I mean, do you expect to replicate someone else’s grow exactly but then like get a completely different harvest?
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Is that a Clydesdale, or coal mine pony cause you know one has to have a metric to compare 
And are you measuring a gram.meter or gigameter “gm”
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If you’re talking Clydesdale then you need to use pennywieghts per Watt / furlong squared. 
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If you look back at some of my earlier posts, I went over why those metrics favor some grows over others for purely math reasons.
Like @ReikoX and @Mr.Sparkle have both said - there is no metric that can fairly compare all our grows. Dont forget that grams are just as fuzzy as watts in this. Well, thats not true. Dry grams are at least a measurable quantity and tend to fall with a relatively narrow range. I say narrow compared to watts, but its still a large % variation possible.
LOL!! I have been out pedanticified!! Or is it pedanticled or pedanticlized? (Thats a real word Im sure) 
Good catch!!
By the way, my high school physics teacher used to ride me on that exact thing - keep the darn units straight or your answer is meaningless, and WRONG! 
You two missed the part above where grams have nothing to do with watts, or fixtures or photons or anything to do with light???
Grams/watt (I have to spell it out or @Mr.Sparkle will ding me again!) is just as perfectly useless for tracking your own grow as it is for comparing different grows.
The instant you say grams per watt you are declaring that g/watt is a ratio (oh man I hope thats correct!). You divide the first number by the second and you get some sort of constant. Thats what a ratio is. A ratio declares that there is a relationship between those two things that can be calculated.
Its like miles per hour - MPH. You take 60 miles and divide by the time it takes to get there and you have a speed. That speed is a ratio. Its math.
The key thing here is that the math for a ratio always has a solution ANYONE can calculate, and or measure, because there is a fixed relationship between all the parts. The ratio is fixed. Its real.
The math works no mater which way you calculate it, or who calculates it. Anyone can measure time and distance and do the math and get the same exact answer every single time. You know that with a fixed speed, if you change the time, you must have a different distance by the same % or the answer is wrong. You can take any part of that formula and solve for the rest.
Grams per watt is NOT a ratio because there is NO relationship between watts and yield that can be calculated or even guessed at. The relationship is not only constrained by upper and lower limits - which are unknown and highly variable - but no one has any idea where their grow falls on that graph above - which means you have no idea what effect changing either grams or watts will have - if any.
No one here can tell me that if they had a yield of 1000 grams with 1000 watts, what would the yield be if you had 900 watts or 1100 watts or 500 watts or 1500 watts.
No one.
Thats because if you go from 900 to 1000 watts your yield might go up a tiny bit or it might go down a tiny bit or it might not change one single gram, or it might go down a lot if you kill the plant from light stress.
How the hell does it make ANY sense to base your personal efficiency on something when you have no idea at all what difference it makes - if any? You cant even guess if it will go up or down with any certainty.
Grams/watt is ALMOST as valid as grams/electrical outlet, or grams per cat, or grams per empty nute bottle, or grams per pound of soil mix you threw away on the previous grow, or any other totally random “ratio” you want to invent.
Grams/watt has zero meaning. It is an invention that is not real.
At all.
Not even vaguely.
It is beyond useless because it is deceptive. It pulls attention away from things that actually DO have a predictable relationship with your yield.
Watts dont even have anything to do with your costs. You cant calculate costs based on watts alone.
Watts are useless.
And thats your public service announcement for today.
holy shit larry. facepalm
I think you will find there is a direct relation to the number of photons the plant gets and the number of grams of bud it produces. You have to stop galloping past the talking points. I recommend a good viewing of bruce bugbee ok?I know it’s fucking kryptonite, but you have to stick with me.I mean ok I would REALLY appreciate if you came and said something like ok joe how the fuck do photons equal grams of buds. Then I can produce said graphs from the phd, you don’t have to come in and shit all over it then wait for me to produce some data to go along with the conversation. It’s not healthy for the conversation. I’m saying that as your friend, that’s for real. I mean, for me, I don’t actually care, because doing something like that in the conversation doesn’t really have any effect. It could get some people agitated though. Unless that’s what you are going for? All I can offer is that debates have rules? ok! Maximizing Cannabis Yields with Dr Bruce Bugbee Go view that shit on youtube and he will show you how the number of photons raining down on the plant affects the yield. I’m sorry it’s kryptonite but please eveyone has to view that shit, I mean the entire universe.
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Not trying to agitate. If it came across that way, I do apologize. However, Its obvious to me that you did not read my post, and I admit to feeling some frustration. If that frustration is showing through, again I apologize to all. I am still fighting kidney stones and that can make me a bit grumpy too. Sorry!
But - I stand by my position. Watts is a 100% useless metric with zero value and has no relationship to grams of yield that anyone can determine, or calculate or even guess at with any accuracy.
Sure, there is a relationship between photons hitting a leaf and grams of yield. Zero photons = zero yield, but thats the ONLY known point on the graph. I am 100% positive Dr Bruce Bugbee did NOT provide a formula linking grams to watts or even grams to photons.
I am willing to bet serious money he cant answer my question either - how many extra grams do you get if you add 100 watts to your grow? How about take away 100 watts?
Thats because watts - all by itself - has absolutely nothing to do with photons or grams or anything else.
You cannot even begin to calculate the photon density or the DLI or the actual energy delivered per sq ft or per plant or leaf or anything else from watts alone. You cant because its leaving out too much critical information.
And even if you skipped watts and went to a real energy delivered metric - the relationship between total energy delivered and total grams of yield is still not a linear relationship. There are still those two limits or discontinuities at the upper and lower range of how much energy a plant can handle. No one - not even a PHD - has any clue where any particular plant falls on that graph, and you cannot calculate it from watts alone.
There is no formula anyone can use to go from watts alone to anything useful - unless you add in all sorts of additional factors. Factors that are not part of g/watt.
I cant help but notice that no one has even tried to answer my questions about exactly how grams relate to the watts number printed on the side of your fixture.
Lets make a list. Any single item on this list is enough - all by itself - to totally discredit g/watt.
Any single one.
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Which “watts” are you using? LED watts or HID watts or florescent watts, or Mars Hydro watts or watts at the wall or watts on the label, or average watts or peak watts or 18/6 watts or 12/12 watts or 24/0 watts?
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The inverse square law - how far is the light from the plant? 6 inches or 6 feet or? The difference in energy felt by the plant over that change in distance is difference of 144 times. Well, not really, because our lights are not point sources, but you get the idea. Even small changes in the distance to the light make huge differences in energy delivered.
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That graph I posted above. Plants have a lower and upper limit as far as light vrs growth. Too little light = zero yield. Too much light = death and zero yield. In between its anyones guess what the relationship is. Increasing watts might increase yield or lower it or make no difference at all or kill the plant. It depends where your particular plant is on that graph, and no one has any idea where that is. Not to mention, the graph will be different for every single plant.
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Which grams are you using? The range on how dry “dry” is that I have heard varies from 21% to 28%, but how many people actually measure it? Exactly how much trim, etc is included? How about small buds? How small does a bud have to be to not count? What if you’re not smoking it? The way @nitro figures it would be vastly different from how I figure it. He smokes and is picky. I dont smoke and want every single trich I can get for my green dragon. I would bet my “grams” from his harvest would have been way higher.
There are more, but Im hurting, so I will quit there. Besides - Any single one of those is more than enough to kill g/watt.
If you want to continue using grams/watt thats up to you, but I wasnt kidding or exaggerating when I said grams/outlet or grams/cat was just as valid or useful.
At least grams per cat is sort of funny
One more time - sorry if I came across the wrong way before. Dont want to start any fights or piss anyone off. I just want to kill g/watt!
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voiceover: this is yield, and this is an input parameter DLI, daily light integral.
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I hope you note that that proves exactly what I have been saying
That is DLI vrs g/sq meter. It is not g/watt.
You cannot get to DLI from watts alone. Especially label watts, but wall wats as well. Watts alone does not get you to DLI. Also, you cannot get to g/sq meter from grams alone.
His graph is cool, but has zero to do with g/watt.
Also - his graph clearly shows the discontinuity on the lower end of the energy scale. It also shows the slope of the graph is not linear. There is no simple equation that links even his DLI with g/sq ft. Its empirical - not mathematical. He didnt extend his graph far enough to the right to clearly show the hi end drop in yield from too hi a DLI, but you can see the trend flattening out to the right.
So, thanks for posting proof from a PHD of everything I have said.
P.S. Its in a YouTube video, so it must be true 
By the way, that graph shape is typical for many efficiency curves, but it doesnt extend out to the right far enough to show the entire progression.
I guess he didnt want to kill his plants for some reason
Edit: also note that he is showing the graphs for two different plants and they have very different yield rates for the same exact energy input. Another point I have been making.
ugh. I really meant you should watch his video or all of his videos. Empirical data means it’s real world. So here’s how it works: you can see his inputs on the growing of the plants - they are well documented.
you can replicate his work with clones of the plants he used and be reasonably assured you should get the same result, right? I mean, if you can replicate what he does exactly the results should come out exactly, or else it’s all made up, right? We understand margins of error ok. I mean you can say yes or no to those 2 questions.
Then, isn’t it reasonable to assume that if he didn’t fabricate it all, then the graph he shows should be hugely predictive of the grams per square meter at those DLI levels? I mean yes or no?
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Yes on everything except that last part. By the way, I am not disputing his graph or how he collected the data or what he is talking about. I happen t agree with it all.
He agrees with me and his graph proves everything I have been saying all along
As I said before - you cannot get from watts to DLI. You just cant. There is no way to even make a wild guess what DLI you have based on your watts - label watts, wall watts or what ever. There is no link and no relationship no correlation between rated watts or watts draw and DLI. There are way to many other variables involved in calculating DLI and none of them have to do with watts on the label. You can easily get the same exact DLI with vastly different “watts” from the light. Orders of magnitude difference.
You cannot say I have a 1000 watt light therefore I have x value DLI. There is no relationship between watts alone and DLI.
Grams/cat has just as much relationship to his graph as g/watt. Its like apples and oranges only worse. More like cats vrs watts.
I am NOT saying he is wrong. Just the opposite in fact.
Its just that he is not saying what you guys think he is saying. He is not talking about g/watt. His graph is in no way related to watts, and you cannot get to his graph from g/watt.
Metrics won’t work for a non standardized system period.
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nothing to do with watts, put the watts aside for now. It was illustrating the relationship between grams of bud produced at certain DLI levels which means the number of photons falling on the plant is directly related to the grams of bud. right?
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Its more complicated than that, but sort of yes, but with a fair amount of no not really directly. Directly to me implies a more or less straight line slope on the graph, and also that the results are the same every time or can be predicted or calculated. That graph clearly shows none of those things are true.
Remember these are empirical numbers he is playing with and only cover a small range - the range he was concerned with was close to the optimum range or trying to find that optimum.
But the graph clearly shows the relation ship is very different for different plants. Look at the difference between cherry and trump. Both the slops and the absolute values and the rate of change in the slopes are all very different. That basically means you cant use the numbers from one plant to predict what different plant will do when you change the DLI.
That graph tells a lot of things that may not be obvious at first glance. Im too messed up to go into more detail now. More later.
P.S. Im glad you finally realize watts has no place in this. 
Yes! Exactly what Ive been trying to get across.
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lol don’t worry larry we’ll circle back to watts.
“Directly to me implies a more or less straight line slope on the graph, and also that the results are the same every time or can be predicted or calculated. That graph clearly shows none of those things are true.”
And yes, like I explained there are margins of error, it’s not like you can exactly replicate everything someone else did or replicate even what you did exactly. The universe doesn’t work like that. And yes! His chart is based on a comparison to the DLI you would get outdoors! But, of course if you did exactly what he did you should get the exact same results…unless it’s all fabricated in which case bugbee’s reputation as a scientist would be in the shitter.
One of the important variables that is entirely beyond your control is the genes of your cannabis plant. So that’s why, there are two lines to indicate the yield of strain “cherry” and “trump”. Each strain with each different dna strand does something different - they are as unique as you or I.
“Remember these are empirical numbers he is playing with and only cover a small range - the range he was concerned with was close to the optimum range or trying to find that optimum.”
In an experiment, you have to control all the variables except the one you are testing to see if it makes a difference. So now, bugbee has developed a baseline of cannabis growing with that chart, so he can compare the yields of different strains at DLI 60 - if that’s what he wants. He’s picked 60 due to the fact it’s the same DLI as a sunny summer day.
“But the graph clearly shows the relation ship is very different for different plants. Look at the difference between cherry and trump. Both the slops and the absolute values and the rate of change in the slopes are all very different. That basically means you cant use the numbers from one plant to predict what different plant will do when you change the DLI.”
genetics my friend, are the ultimate machine that does the final yield determination, like I said above.
Just wanted to say larry your post above there I quoted was really good, you know, for the conversation! I really appreciated it! Remember that’s not a bullshit lie - I really do appreciate it.
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DLI is based on umol.second/m^2. Measured directly using a PAR meter then multiplied by total time. It is nearly a fundamental measurement. Even then, you have to be careful since PAR is generally the total number of photons over a square meter which means measuring an accurate value is a challenge. But once you have an accurate number, it translates well into evaluating the physical needs of a plant. If everyone has a PAR meter and can accurately assess the DLI (which will change during the grow period), then you’ll have one (of several) base metrics that could be considered ‘scientific’ and reproducible. Even PAR may not be sufficient in some cases (for things outside of PAR)…
Will you get exactly the same results as Bugbee? No, he’s giving you a generalization for a specific scenario. His research papers call out specifics on the environment which are held stable during the experiment. Other variables will become evident including things such as CO2, nutrients, air flow, genetics, etc. CO2 enrichment vs no enrichment is an example where the curves will shift significantly. But, you will have a fundamental point from which you can assess other inputs into your system where the trends will likely be similar as long as there is no known limiting factors. The generalizations give you just that, generalizations on how to achieve something similar but they rely on other similar system inputs, too.
The photons you are receiving at the plants is far removed from the system power in Watts. There are a multitude of variables that need to be accounted for in order to convert to PPFD (as used in the DLI). That includes efficacy, distances, angles, temperature, spectra, etc. It’s a lot of information to track. PPFD avoids many of those variable since it’s fundamentally measuring the photons hitting the leaves.
The use of Watts is simply messy and prone to lots of inaccuracies because it’s easy to ignore the other variables that dictate the number of photons that plant receives. It can not directly translate into DLI. You’d have to make the conversion with a lot of calculating or estimating.
Touch nothing, change nothing, then sure Watts could be used for a relative comparison for the exact same set-up. It’ll break down as soon as something changes and it would be difficult to account for those differences.
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Here is why grams per watt was very important to many of old school guys… back in the day when we were setting up a growroom at a house we were always limited by how much power we could pull from the panel…We simply didn’t have the option to run a pile of lights as the electrical infrastructure wasn’t there… 100% our limiting factor was available power limiting how many lights we could run… For us the most critical thing was growing as much weed as we possible could with the amount of power we had to work with.
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