1 kilo per light - or why gm/watt suck!

Growroom Design
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Whew! Finally someone who ‘sees the light’ and agrees with me!

P.S. I brought that up early in the thread by the way. :wink:

I saw that post, but I still dont see any value there. You would first need to tell me what watts have to do with grams. In your example, if you turned your lights down to 900 watts would you only get 900 grams? Would 1100 watts get you 1100 grams?

What if your light was running 12/12 from seed - do you still get the same yield as running 18/6 and vegging for 3 months first?

How exactly do you reconcile those differences?

What if you had that same 1000 watts but only a single auto you ran for 2 months with the light 6 ft above the plant? Same yield? Its the same watts after all.

Im seriously asking why you think that 1000 watts - all by itself - has anything to do with your 1000 grams. What you are saying is that the light is the only thing that matters to the yield.

Plus, are you seriously saying people dont post their gm/watt numbers to compare their yield to other peoples grows? Gm/watt is a dick measuring contest. Period. It always has been and always will be. There is no other reason anyone posts any data, pictures, etc about their grows.

Well, unless they are asking for help maybe. Everything else is some variation of “Look how cool my roots/buds/trichs/hash/etc/etc/etc is!”.

Being proud of your grow and growing skills, and showing them off, isnt bad. Thats human nature. I have never met anyone who, at least secretly, didnt enjoy showing off a job well done.

But it is still a dick measuring contest.

I cant help but notice that none of you have even tried to answer any of my questions other than to say its imperfect, but everyone uses it.

Are we all lemmings running off the cliff together because “It will only hurt for a few seconds, and thats what everyone else is doing, so Im going along with it.”. Seriously?

Thats exactly what your arguments boil down to.

I happen to think that if at least a few of us started to point out the fallacy in gm/watt, eventually, we would start to make some progress in eliminating this bit of stoner science/old wives tale.

Dont you guys want to have more real science in your grows and less fiction?

I am having doubts though… :smiley:

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142

It occurs to me another problem would be trying to get at least two people to agree on which exact metrics to use, and exactly how to calculate it.

Based on this thread, I doubt thats possible :slight_smile:

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I see that is true but are we not all looking at effeciency which is bud produced vs watts used (power/expenditure) so you can get the most out of our spaces wether small or large?

… Plus every variable that can be effected in a constant enviroment… Haha.

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ok larry take that post, and as I said, edit out the part where I mentioned what wattage of light I was using and you are left with the statement I hope I get 1 Kilo, ok so how is “I hope I get one kilo” indicating what I used to get that kilo. without mentioning the watts of the hps bulb there is no information. I could have easily said I hope I get a single gram. So, aside from your strawman argument about “I have to explain how watts translates into grams” when there is no indication anywhere that anyone even made that claim. Then how is watts useless information in my post if without saying it you have absolutely no idea what I’m saying because it’s devoid of any context or information.

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I really like the formula @LemonadeJoe posted above. I think (at least in my case) a “garden efficiency index” or something similar to calculate net cost based on light hours is the best of all worlds because time is the universal constant in our case and can be directly comparable between different kinds of grows - for example a short grow with a 1000w lamp vs a long grow with a 250w LED. Plus it would allow me to calculate actual energy cost. Something I should be able to do given the data I store and is definitely something I want to code in the future

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146

How about the ultimate metric $ per gram

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147

I really do like that calculation too except when i try to apply it to my grow i will have to fill the whole space at once as my autos are all out of sync or i will have to do an estimation saying my plant takes up 6x6 inches which means in a 2x2 (my lights coverage area) id get 16 x the yeild

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not to mention that lights have come a long way since the gram/watt rule was first invented

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No doubt . A true 1000 watts of led will blow a 1000 watt hid away I think now . 20 years ago I remember they weren’t even an option.

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yawn OK, well, I mean nobody wanted to actually get in touch with why I can use grams per watt. It’s easy! So if I am getting .5 grams per watt under 600watt hps bulb then I’m like hmmm… could I see if there is some kind of higher efficiency? how DO I test for that? So then I get out 600watts of LED light and I plug those babies in. Then I’m like ok… I got (1gram per watt/.1gram per watt/100grams per watt) so then I can make a decision on if the light source I just tossed up is helping me, or kicking me in the balls, because all other parts of the grow are controls. So the only difference in the experimental groups is the new light source using the same number of watts. You do understand that’s how an experiment like that works?

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So who’s got the record for G/watt

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lol that’s some classic humor there nitro! Ever seen “South Park - T.M.I.” where cartman has to join anger management after he learns his penis is the smallest in the class?

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Every outdoor grower… Apologies

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in my 20odd years growing i have never weighed my grow, i suppose if my grow was perfect i might want brag about it or enter a competition, i like showing off my plants though. is it just dry bud without leaf and stalk that’s weighed

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Sorry man. I have been ignoring your post and you are asking legitimate questions.

Yes - thats a good experiment and would give you a valuable result - for your grow. Its still not a good way to compare your grow to mine.

Part of the problem is I think too many people think the light has some magical effect on yields. All this battle between LED’s and HPS etc has over looked some things.

The main one is the lights really dont make that big a difference.

Yes, going from 500 watts HPS to 500 watts LED does make a noticeable difference, but thats a relatively big change in actual photons delivered to the plants - especially if you take advantage by moving the LED closer than you can get the HPS. You can easily get double the amount of real light energy to the leaf doing that - with the same “watts”.

But - doubling the watts makes maybe a 5%± difference in yield - and thats only if you can keep from frying the plants and killing them with all those extra watts.

Now Im assuming you are already giving your plants a reasonable watts/sq ft for your plants. If so, you are never going to see big changes in yield - either way - with small changes in watts.

The relationship between watts and yield is non-linear. There is no simple formula for th relationship between watts and yield because there are thresholds at the lower and upper end.

As you lower the amount of light, the yield will drop some, but when you get to some point it suddenly drops off dramatically. The same at the upper end. Increasing light will add some extra yield, but at some point, you induce light stress and begin to kill the plant.

The area between those two extremes is relatively flat.

This is a crude idea of what Im talking about.

gmwatt
gmwatt1199×682 27 KB

Most growers operate in that relatively flat portion of the graph where any changes in watts makes very little difference in the yield. More importantly from my perspective - there is no way to calculate or really predict the difference in yield for any given change in watts.

If you are already running on the low side as far as watts/sq ft, then increasing the watts should give you some small increase in yield. But if you are at the peak efficiency point already, increasing the watts will actually lower your yield.

Unless you know where you are on that graph - you have no idea if increasing watts will make any difference either way - and it could go either way. You might be able to tell if the plants are showing signs of light burn, but I dont know of any other indication.

This is why referencing grams to watts makes no sense. There is no real connection that can be used repeatedly by different people with different grows.

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or 4 MH in the sky

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you know larry, I did underestimate you, and I salute you! :vulcan_salute: I thought for sure you would think I was the ultimate turd after pressing the point. I have never been so happy to be proven wrong. and that’s no sarcastic bullshit. The fact you came back here and posted those words, really bumped up my level of respect.

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So want to try gram per day per cubic foot? @anon32470837 @JoeCrowe
Please point out the downfalls of this metric?

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yah it uses some kind of measurement I never heard of…foot?? :wink: lol you have to include the number of photons that hit it in the grow cycle as well. grams per square meter per photon count. That way you account for all the variables that aren’t zero gain, like dehumidifiers or fans.

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How do we calculate photon count without a fancy device?
I would do cm For accuracy buuut you know most people can’t deal with that.

Edit: attempted googling and saw numbers, brain threw an error code and said close the window before you get a headache :rofl:

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