Grams-Per-Watt is an erroneous measure of productivity

[StealthyStalks]

I have only been a member for a month or so, but I keep reading people using the gram-per-watt as a measure of productivity. Grams-per-watt is an erroneous measurement! So, IF they are going to use energy input as the deciding factor of efficiency THEN they need to use G/KWH.


If two growers growing the same clone and both using a 600w HPS get 600 grams from their harvest, it would sound like they are both equal in productivity, right? But if the first grower did it in 60 days and the second in 83 days, it's obvious who the most productive grower is.

Starting from rooted clones:

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 (.4x18x23 + .6x12x60)

Ideally one needs to calculate all the kilowatt hours used in the whole process from cloning, vegging and flowering to give a true picture of productivity using the same clone mother.

Use the Grams-Per-Kilowatt Hour measure when trying to improve your growing method.

The original post was edited to keep the knitpickers and assholes happy. I doubt it will do any good though.

 

[praisehim.]

^^ very right there sir. ^thats the way to do it.

 

[Sam the Caveman]

I agree, gpw is only comparable when the veg and flower time is put into perspective.

I have seen other members discuss gpw per month of flowering time which is more accurate but still doesn't account for veg time.

 

[sour power]

i havent even got to 1gpw yet but ive came close.damn! i cant wait into when im hitting it all the time

 

[Nibiru king]

Just made 2230 Grams on 1800 Watts (3 x 600W)
Vegged 5½ week
Bloom 8 Weeks

 

[headiez247]

How about just lbs per light.

<1 = needs work
>1 = Good
>2= Amazing

I started at less then one, now I'm at 2+ so far with this perpetual new way.

 

[PeteWeedSeed]

I know the errors are more confusing then that. I never cared when people say their GPW
Since some strains require much more time to bloom to full quality and others just grow fast and produce weight.

I only use the grams per watt test on my personal grows to test if my techniques are improving or not. And that's they only thing you can really test with it. Comparing your buddies similar setup won't help much either, the conditions from one grow to another vary so much, its impossible.

Its mostly new growers that don't understand what they are testing, comparing themselves to other new growers. A pointless cycle really... But theres nothing you can do about, new growers log on everyday, too hard and too many to train on proper use of the method.

 

[StealthyStalks]

Just made 2230 Grams on 1800 Watts (3 x 600W)
Vegged 5½ week
Bloom 8 Weeks

Now that is a very respectible productivity!

38 days of veg: 38 days x 18 hours x 1.8 kilowatts = 1,231.2 kilowatt hours.

56 days of flowering: 56 days x 12 hours x 1.8 kilowatts = 1,209.6 kilowatt hours.

Total Kilowatt Hours used = 1,231.2 + 1,209.6 = 2,440.8 kilowatt hours.

Productivity = 2,230 grams divided by 2,440.8 kilowatt hours = .9136 Grams-Per-Kilowatt Hour.

 

[StealthyStalks]

How about just lbs per light.

<1 = needs work
>1 = Good
>2= Amazing

I started at less then one, now I'm at 2+ so far with this perpetual new way.

Because pounds per light doesn't say anything about productivity. You need to know total energy used to calculate productivity and with electricity that would be measured in kilowatt hours.

 

[jm420]

gpw is B/S

 

[thecreeper]

i would like to see people start measuring it with all energy used in the grow, meaning Lights, Fans, Pumps, A/C, everything that uses electricity and is used for the grow should be factored in as well as the veg, mother, and flower rooms. Take all that and then calculate your gpKwh

 

[smurfin'herb]

cannastats had a great section on grow efficiency. They go really in depth on a lot of issues that are completley overlooked by most growers today. I loved that place, wish i could still find it...... I know someone here has it, where u at my friend?

 

[MeanBean]

I like the concept! It must be measured this way!

 

[B00420]

Ultimately, all that REALLY matters is the total end weight...

Who cares really if you use an extra watt here or there....I say use as many watts as you have even if efficiency goes down.

It's not like we're growing tomatoes.

 

[B. Friendly]

i agree it is the end weight. To be simple just figure out if you grew more than last time.
5000w or 5000g's is huge, that's just over 11lbs which would be 2.2 per bulb. That is not easy to do in the slightest. I'll give my best.

 

[TickleMyBalls]

yeah, but how do you differenciate the KWH used for your grow, and used throughout the rest of the house, if you're growing in a house. I think the standard should be lbs. per light, because every decent grower can pull 1-1.5 lb from a 1000w light. grams per KWH is deceptive. If you really want to calculate efficiency, do it grams per 6x6x7 (the coverage area of a 1000w hps) area, per cycle. it's all about producing the most in the least amount of space anyway, not with the fewest KWH. and the price of kilowatt hours is different all over the country, so does that mean someone producing identical yields in cali as someone in kansas is a less efficient grower because it costs them more money for power? It just isn't a logical way to calculate efficiency to me.

 

[StealthyStalks]

yeah, but how do you differenciate the KWH used for your grow, and used throughout the rest of the house, if you're growing in a house. I think the standard should be lbs. per light, because every decent grower can pull 1-1.5 lb from a 1000w light. grams per KWH is deceptive. If you really want to calculate efficiency, do it grams per 6x6x7 (the coverage area of a 1000w hps) area, per cycle. it's all about producing the most in the least amount of space anyway, not with the fewest KWH. and the price of kilowatt hours is different all over the country, so does that mean someone producing identical yields in cali as someone in kansas is a less efficient grower because it costs them more money for power? It just isn't a logical way to calculate efficiency to me.

I have to disagree with pretty much everything you said here.

First off it is very easy to compute your power consumption; every pump, light and fan you use has the power rating right on it. If you want to be real accurate get a watt meter.

Secondly, grams per area of grow space is totally off base when you're trying to show the most efficient method of growing.I could pack nine 600w HID's in your 6x6x7 example, giving them 150 watts per square foot, and force feed the plants CO2. That doesn't make it efficient.

Lastly, it doesn’t matter what the price per kilowatt hour is where you live; what matters is energy consumption. That’s what the cops look for in most states that don’t have liberal laws. That is why it is important for most growers to fine tune their technique so they get the most out of the energy consumed.

Cost is not an issue for most growers, it’s the energy consumed and the red flags that come with the high consumption.

I put this post up to correct the erroneous information being perpetuated on ICMag about using grams-per-watt as a productivity comparison tool. If you want to compute efficiencies then you need to use Grams-Per-Kilowatt Hour.

 

[StealthyStalks]

i would like to see people start measuring it with all energy used in the grow, meaning Lights, Fans, Pumps, A/C, everything that uses electricity and is used for the grow should be factored in as well as the veg, mother, and flower rooms. Take all that and then calculate your gpKwh

Yep, that would be the TRUE way to compare efficiencies!

 

[StealthyStalks]

Ultimately, all that REALLY matters is the total end weight...

Who cares really if you use an extra watt here or there....I say use as many watts as you have even if efficiency goes down.

It's not like we're growing tomatoes.

That's all fine and dandy if you are someone like dongle69 who grows where it is quasi-legal and power consumption efficiencies really don't matter much. Christ, anyone can have a state-of-the-art 50,000 watt system set up under those conditions!

The fact of the matter is, for most of us, we need to grow with the most efficient means possible to keep a low profile because of the legal ramifications.

 

[StealthyStalks]

i agree it is the end weight. To be simple just figure out if you grew more than last time.
5000w or 5000g's is huge, that's just over 11lbs which would be 2.2 per bulb. That is not easy to do in the slightest. I'll give my best.

I was just trying to point out that the grams-per-watt measuring gauge everyone seems to use on here is erroneous. If one must use a gauge to measure efficiency then they need to use Grams-Per-Kilowatt Hour used.