churchhaze
Well-Known Member
Even within the metric system, it's possible PPFD could be measured in units of umol*s^-1*km^-2, it's just that nobody will ever use that unit.
Yields at differant PPFD?
- Thread starter Trippyness
- Start date
JorgeGonzales
Well-Known Member
http://www.angelfire.com/cantina/fourtwenty/yor/prodtable.htm
Some oldschool analysis, and surprisingly accurate when you compare to grow journals.
If the chart is accurate, the difference between incremental lighting steps is pretty small, but adding canopy space is very effective. Moving a 400W light from a 2x4 to a 4x4 can nearly double yield with the same electric bill.
Also makes GPW seem even sillier.
Some oldschool analysis, and surprisingly accurate when you compare to grow journals.
If the chart is accurate, the difference between incremental lighting steps is pretty small, but adding canopy space is very effective. Moving a 400W light from a 2x4 to a 4x4 can nearly double yield with the same electric bill.
Also makes GPW seem even sillier.
Rahz
Well-Known Member
Oh, well the difference in my experience would be close to 33% more yield per sq/ft using 800 PPFD. The yield per par watt would be similar but for any particular space higher wattage is higher PPFD. Sorry if I was unclear, what I mean to say is that there may be no relevant increase in yield per par watt comparing 600 to 800.
Jorge's link tells a different story though and I wouldn't call my test results definitive. In the case that my results are wrong, there's still some sense in higher PPFD if you want to increase yield but can't or don't want to increase the space involved. 800 PPFD in a particular area will out yield 600 for sure. We're just trying to figure out by exactly how much. The table in that link seems to have quite a bit of solid work behind it so it should be helpful.
Trippyness
Well-Known Member
This is true. Canopy level and veg time as well as genetics.
Trippyness
Well-Known Member
That is helpful. By how much is the question.
Trippyness
Well-Known Member
Was no CO2 talk, but I always have CO2 especially in Veg.
Nice to see you here mate.
You got any opinion by how much 600 vs 800ppfd affects yield with same space and plant count?
Growmau5
Well-Known Member
I posted some metrics on a CXB harvest video near the end. I calculated like 650 ppfd for my 700ma setup over a 4x8. Gpw was great at that amt of light with no co2 supplementation. i don't have anything empirical to contribute at growing with cobs above 800ppfd. But I will very soon 
dandyrandy
Well-Known Member
Thank you.
guod
Well-Known Member
my Printer - dot per inch - dpi
my screen resolution pixel per inch - ppi - and the size of the screen is given in Zoll just as my car tyres
all electronic parts are in inch - fraction of
and many more...
we also deal with miles - aircrafts and ships mostly
no gallons, oz or pounds in daily use here ... thanks good
we know how to handle this
my screen resolution pixel per inch - ppi - and the size of the screen is given in Zoll just as my car tyres
all electronic parts are in inch - fraction of
and many more...
we also deal with miles - aircrafts and ships mostly
no gallons, oz or pounds in daily use here ... thanks good
we know how to handle this
Abiqua
Well-Known Member
strains?I posted some metrics on a CXB harvest video near the end. I calculated like 650 ppfd for my 700ma setup over a 4x8. Gpw was great at that amt of light with no co2 supplementation. i don't have anything empirical to contribute at growing with cobs above 800ppfd. But I will very soon
medium?
churchhaze
Well-Known Member
There is no such thing as 800 PPFD.... PPFD is not a unit!!
Trippyness
Well-Known Member
Will have a look. Ps keep up the videos. Really great stuff.I posted some metrics on a CXB harvest video near the end. I calculated like 650 ppfd for my 700ma setup over a 4x8. Gpw was great at that amt of light with no co2 supplementation. i don't have anything empirical to contribute at growing with cobs above 800ppfd. But I will very soon
Trippyness
Well-Known Member
On his channel.strains?
medium?
Trippyness
Well-Known Member
It is a unit. Getting even PAR to the canopy. Really have no idea how you can say that.
churchhaze
Well-Known Member
Your screen is not 1080 resolution. You don't buy 1 volume of gasoline. You don't drive 1 distance of road. It's not correct English.
"Resolution" is not a unit. "Volume" is not a unit. "Distance" is not a unit".
Your screen has a resolution of 1080 x whatever. You buy a volume of 1. You drive a distance of 1.
When you put a word right after a number, the number is counting units of something, and none of those words are units.
churchhaze
Well-Known Member
It's not a unit. umol*s^-1*m^-2 is the unit most commonly used for PPFD, and is what you all mean when you say "800 PPFD". PPFD is not the unit, it's a variable.
Growmau5
Well-Known Member
@Abiqua @Trippyness because it applies so well to what we are talking about here, ill link to the spot in the video where i report the results. its a blue dream dominant strain in 5g canna coco pots.
@churchhaze it looks like I was indeed using more like 750-790 umols of photons per second per square meter.
8:03 mark (wont let me link to that exact spot)
@churchhaze it looks like I was indeed using more like 750-790 umols of photons per second per square meter.
8:03 mark (wont let me link to that exact spot)
Rahz
Well-Known Member
The YOR analysis seems much more scientific than what I have done, so you can comb through the methodology and use the lumen chart to get an idea of the percentages they came up with.
However, I'm not experiencing the same results and in their conclusions it states: coefficient = 1.386 grams more per square foot per 1,000 lumens which is just not gelling at all with my experience. I know you may not want to devote the time or resources, but if the issue was important enough you might try setting up a couple small test areas and seeing what you can come up with at 600 and 800. My results were in hydro with similar nutrient PPMs, but container size, brand of emitters, tent size and shape were all different, so there's plenty of room for error in my setup.