Why go 24 hours lights on??

[Rumpleforeskin]

Opposing viewpoints was censored.

 

[opt1c]

seriously; i was willing to do a side by side
same room; same make of tents; same strain; same nutes; both fed off float valves from a similar reservoir in dwc; etc...

spurr told me i was full of shit and wasting my time because i wasn't measure ppfd

and then when i pointed out the fallacy of his argument as he was implying that every researcher before the advent of ppfd measurements was full of shit and wasting their time

he conveniently and completely ignored my post and never replied to it while spending hours replying to other posters who weren't asking real pointed questions

SHIT LIKE THAT... THE PICS OF YOUR GHETTO ASS LAME BLUE DREAM PLANTS IN YOUR GALLERY(and i've NEVER seen such shitty pics of blue dream online) ON TOP OF YOUR HOLIER THAN THOU ATTITUDE RUBS ME THE WRONG WAY

so if you want to keep calling bullshit on people you better start backing up your claims with photographic proof; if your plants can't back up your claims than what the fuck can; a reference to a study comparing a C3 plant; so every c3 plant is the same eh

indicas are c3 yeah?
sativas are c3 yeah?
so they grow the same cuz they are c3 eh?

but i guess since you read an article about c3 plants you're irreproachable

You want to talk like you know shit back it up bro; this shit is getting old fast
Step up or step off
You're medical but scared to post pics of your work or you're full of shit and don't have pics of your work cuz you've never put in any work outside your mind or your theories never measured up to your hypotheses and you're too proud to admit it

Put up or shut up

honestly; i'm really close to holding you in the same regard as mistress (and if you think i'm full of shit just do a search through her pervious posts)


hey sprurr; why don't you tell us how much ass led lights kick while you're at it

BTW; if icmag is about growers and selling seeds... y r all the mods on the nuts of a guy who don't buy ur seeds or grow em out? from all the other users you've banned you've lost a lot of grows by a lot of users who bought seeds from you site

but if u want to become a family oriented bs(i mean unapplied scientific conjecture) site go for it... last time i checked we were about overgrowing the world not measuring or dicks on a PPFD scale

and yeah spurr; you can constantly troll the stupider posters that make it easy for u but continue to ignore my posts and pointed points

i take pride in backing up all the shit i say as best as i can; often as financial cost to myself but i'm all about karma so i guess that's why i'm still here.... spade is a spade... dick is a dick... and an asshole poster is an asshole poster

and no that's not all i got to say so i'll be nice and save the real good stuff for later

opt1c aka the mofo tired of icmag shooting itself in the foot... seriously a year ago this was a different site; full of growers sharing their grows; results; experiments; etc...

remember yamaha_R1; and now we got krunch who's like the last large grower left on this site; i remember when krunch was one of many big growers but now everyone hates on him

so you're trying to sell seeds on icmag but you're step by step alienating those who buy seeds from your site by allowing the mods to turn this place to complete shit... really sad; used to be the best and ONLY site on the net worthwhile after OG; i'd be lying if i said that was still true

so fuck a side by side we will just take sprurrs word for it cuz the work in his gallery speaks for itself (and if it doesn't step your gallery the fuck up and make me eat my works i'd be more than happy to)

and i'm in cali; i got a job where i travel all over the state, hell country even; i got it cuz of my grows and i go to hydro stores and dispensaries for my job... so if you're in cali and u don't want to post it up pm me and we can meet at a med dispensary anywhere in the state... u bring ur work i'll bring mine and we can see whats up.. hell i'm about 3 weeks out of my new harvest and i'm so confident i got it locked down i'll bring just that against anything you've done that you still have

your end result of all your scientific background vs my end result with my background and experience

and just so u don't think i'm setting u up i'll throw it out there now... phi beta kapa in college and national merit scholar in high school are the only academic accolades my stupid ass has ever received although i'm sure i pale in comparison to your vast intellect

so lets do this

 

[Madrus Rose]

Hey again JapanFreaker, nice to see you aren't cursing at everyone any longer

I know you wrote this to Dave, but I'm here now and figured I'd toss in my 2cents:



Do you not understand that too much light (either as instantaneous irradiance, i.e. PPFD, or over the whole day, i.e. DLI) is not good and can be very detrimental? Too much light can reduce rate of photosynthesis just like too little light; the goal is to provide the 'sweat spot' of DLI in 16-18 hours.


I've done it, and have already reported that 18 hours gives faster growth. And FWIW, ideally daylength would be 16-17 hours, 18 hours max. Once daylength excess ~17-18 hours, assimilate and partitioning is reduced, as is the amount of active rubisco (which is needed for photosynthesis), and thus rate of photosynthesis is reduced too, etc., etc.

Using at most 18 hours of daylength with high PPFD, and thus high DLI, allows for both high rate of photosynthesis (Pn) and high net rate of photosynthesis (Pnnet), along with allowing for very valuable light independent reactions during the dark cycle.

Talking "daylight" perhaps , but not for artificial lighting
alone ... and also depends on the crop


** What DLI is needed to grow high-quality transplants and finish plants?

The answer depends on the crop, but a common target minimum DLI inside a greenhouse is 10-12 mol·m-2·d-1. Plant quality generally increases as the average DLI increases. In particular, as the DLI increases, branching, rooting, stem thickness and flower number increase and sometimes plant height decreases.

http://www.gpnmag.com/Daily-Light-Integral-Defined-article7534


But u have convinced me to try turning
down the veg area to 20/4 ...hoho!

** This song goes out to our friend --> JaFreak, aka "Y~K~Who" ,
aka ---> Bannana Boy!

http://www.youtube.com/watch?v=A42SkxHo-x4&list=QL&playnext=6

 

[spurr]

@ opt1c,

I didn't respond to you because it's not worth the effort, you're a joke and make insanely asinine comments and arguments. Your level of understanding, power of literacy and observation are laughable. I already explained to you why using a simple side by side is a fail, but you ignored what I wrote and made more asinine comments thinking you're a smart person (clearly you're not).

FWIW, the S1 blue dream were so stretchy do to problems phenotype (some plants were much shorter and some very tall), and with my temp control and ballast breaking and messing up with some PGRs. I didn't even finish them, I took them down due to their height before they finished flowering. It's obvious I wasn't trying to hide them, otherwise I wouldn't have uploaded the pics for a thread in OFC. Nice that you pointed out the blue dream but not the other plants, lolz. You fail yet again.

 

[spurr]

ey again JapanFreaker, nice to see you aren't cursing at everyone any longer

I know you wrote this to Dave, but I'm here now and figured I'd toss in my 2cents:

Do you not understand that too much light (either as instantaneous irradiance, i.e. PPFD, or over the whole day, i.e. DLI) is not good and can be very detrimental? Too much light can reduce rate of photosynthesis just like too little light; the goal is to provide the 'sweat spot' of DLI in 16-18 hours.

I've done it, and have already reported that 18 hours gives faster growth. And FWIW, ideally daylength would be 16-17 hours, 18 hours max. Once daylength excess ~17-18 hours, assimilate and partitioning is reduced, as is the amount of active rubisco (which is needed for photosynthesis), and thus rate of photosynthesis is reduced too, etc., etc.

Using at most 18 hours of daylength with high PPFD, and thus high DLI, allows for both high rate of photosynthesis (Pn) and high net rate of photosynthesis (Pnnet), along with allowing for very valuable light independent reactions during the dark cycle.

Talking "daylight" perhaps , but not for artificial lighting
alone ... and also depends on the crop

Growing inside under artificial lighting it is easy to provide more light (PPFD) than the sun. That is why when growing inside it's very easy to provide too much light to plants and cause photoinhibition like reduced Air-to-Leaf Vapor Pressure Deficit, reduced rate of photosynthesis, etc., and actually damage leaf tissue such as leaf bleaching.

Outside PPFD peaks under the sun (in the most sunny areas of the world like Hawaii during summer time) around 1,800-2000 PPFD, but only for a few hours a day. Inside, under a 600w or 1,000w HPS it's easy to provide 1,500 PPFD and higher, up to ~2,000 PPFD (depending upon how close the lamp is to canopy, quality of reflector, use of digital ballast, age of lamp; not to mention usage of newer advanced HPS lamps (ex. Ushio HiLux Optired), and a (slow) light mover). And if a grower is measuring instantaneous irradiance in less than a meter^2 (ex. umols/foot^2/second) it's very, very easy to provide more irradiance than the sun, e.g. > 2,000 umoles/foot^2/second.

Thus, under HID, a grower can not only provide more instantaneous light than the sun as PPFD, but provide more DLI too. In fact, using 600w to 1,000w HID very easy to provide higher DLI than the sun provides in most places in the world, due to the natural PPFD bell curve of sunlight.

It's a common misunderstanding that an HID can not provide as much light as the sun. In my grows I provide more DLI than the sun as found in most areas of the world, as do many other growers due to the bell curve of sunlight PPFD, over a day. There is no irradiance bell curve under an HID except for the first 10-20 minuets of day if using a magnetic ballast. Under an HID it's the same irradiance all day long. That is the big difference in terms of DLI and why it's very easy to provide higher DLI with HID than DLI from the sun.

If a grower properly uses high wattage HID with proper usage of UV-b, they can provide a better light source than the sun, very easily.

** What DLI is needed to grow high-quality transplants and finish plants?

The answer depends on the crop, but a common target minimum DLI inside a greenhouse is 10-12 mol·m-2·d-1. Plant quality generally increases as the average DLI increases. In particular, as the DLI increases, branching, rooting, stem thickness and flower number increase and sometimes plant height decreases.

http://www.gpnmag.com/Daily-Light-Integral-Defined-article7534

10-12 mol/m^2/day is far too low for cannabis, and other plants that can use very high levels of PPFD (i.e. ~1,500). 10-12 mol/m^2/day is better for low light crops, not for cannabis.

But u have convinced me to try turning
down the veg room to 20/4 ...hohoho!

Nice, let us know what you think, but remember that you need to consider irradiance, DLI, etc. Not just hours of day.

** This song goes out to our friend --> JaFreak, aka "Y~K~Who" ,
aka ---> Bannana Boy! lol

http://www.youtube.com/watch?v=A42SkxHo-x4&list=QL&playnext=6

hahaha

 

[zenoonez]

If you want to do a side by side do it. I think the point is that true scientific research excludes all variables that it can and seeks to use the best information or methods to document those tests. Empirical science is fine, in other words do the experiment but what spurr believes is key is the total light absorbed and if your experiment doesn't measure that then it doesn't differentiate between 24/0 and 18/6 in a way that he thinks advances the science. Its obvious that the both of you don't get along but I don't think spurr gets along with many people. Perhaps a disclaimer in your sig would be a good idea spurr. For what its worth Opt1c, I think you are right and I have wrote about the atmosphere at IC before. It certainly seems that we have lost a lot of great growers over the past year or more and it is disheartening to see good growers and members banned. Maybe the two of you should smoke a jay and come back to the table in a less adversarial manner because the two of you pissing on one another doesn't help any of us discover how to grow any better.

 

[spurr]

Perhaps a disclaimer in your sig would be a good idea spurr.

Like what? How about: "if people continually post adversarial messages I will do likewise...especially if they are ignorant and make asinine comments"

I am never the one to "start it", I don't like it anymore than you do, I am always attacked first, ex. by optic1 in other threads. And I am not the type of person to "turn the other cheek" when I am correct.

EDIT:
Because I often show how common belief in cannabis world is wrong, I get attacked much more than the average Joe. That and I don't post like lots of other growers, I tend to be terse. If I didn't try and dispel the many myths of cannabis growers I wouldn't be attacked so often. It's growers ego, when attached to their beliefs that makes them attack me; many people just hate it when they are shown to be wrong; Japanfreaker, bobman, and Optic1 are great examples of that mindset.

because the two of you pissing on one another doesn't help any of us

That is why I have ignored him this whole time, as evidenced by Optic1's lamenting of my ignoring of him, yet he hasn't ignored me, he kept posting adversarial and asinine messages

 

[spurr]

@ all,

The simplest solution for people who want to do proper side by sides, and account for things such as irradiance and DLI, is to spend a measly $199 for a fairly decent quantum sensor to measure PPFD (granted it's not a great quantum sensor and the PPFD will not be uber accurate, but it's far better than the option of not using a quantum sensor).

• Here is a quantum sensor people can use, it's only $199: http://www.specmeters.com/Light_Meters/Quantum_Light_Meter.html

Doing side by sides of 18/6 vs. 24/0 without measuring PPFD and DLI means the side by sides have very little value.

 

[macdiesel]

I have seen a few "Pro 24/0" folks post links and quotes from well know Marijuana experts and authors in this thread. More then random hearsay. Is reading a problem?

I know Mr.Green (I grow chronic) is a key scientific expert for the 18/6 guys .

I didn't see any peer review references cited or anything of that nature. I understand "marijuana experts" being respected, but it seems to me that they are usually applying personal experience which has too many variables and is farrrr from a consensus in the scientific world.

I love the dialog and see some cool points from both sides.

Agreed.

And I hope Japanfreak is not on my side of this issue (will consider changing light cycle back to 18/6 if he is).

Coffee meet monitor. LOL

Rump-I enjoy your contributions to this board, thank you!

 

[The Phoenix]

@ all,

The simplest solution for people who want to do proper side by sides, and account for things such as irradiance and DLI, is to spend a measly $199 for a fairly decent quantum sensor to measure PPFD (granted it's not a great quantum sensor and the PPFD will not be uber accurate, but it's far better than the option of not using a quantum sensor).

• Here is a quantum sensor people can use, it's only $199: http://www.specmeters.com/Light_Meters/Quantum_Light_Meter.html

Doing side by sides of 18/6 vs. 24/0 without measuring PPFD and DLI means the side by sides have very little value.

While I think a series of good side by side indoor grows with slow vegging indica clones from the same plant would be good, I see no need to go out and spend $200 for a meter if your test is side by side under the same bulb at equal distances dont you think spurr?

Lets say you drop the sets of clones from a few plants under under the bulb and pull out one set into darkness for 6 hours everyday. Wouldn't that take the variable out of having two bulbs light output affecting the experiment and eliminate the need to purchase that sensor?

I think a better measurement of effectiveness for an experiment also might be to take the same sets of clones, and give them equal veg time (18/6 for one set and 24/0 for another under the same bulb), then flip them to 12/12 under the same conditions and measure the grams per watt output of each set when they are finished. After all, that would be the ultimate goal anyway since some of the 24/0 advocates claim better production with that light cycle. Couldn't this experiment be done with a few sets of equal clones with one nice 400wt light setup?

 

[macdiesel]

While I think a series of good side by side indoor grows with slow vegging indica clones from the same plant would be good, I see no need to go out and spend $200 for a meter if your test is side by side under the same bulb at equal distances dont you think spurr?

Lets say you drop the sets of clones from a few plants under under the bulb and pull out one set into darkness for 6 hours everyday. Wouldn't that take the variable out of having two bulbs light output affecting the experiment and eliminate the need to purchase that sensor?

I think a better measurement of effectiveness for an experiment also might be to take the same sets of clones, and give them equal veg time (18/6 for one set and 24/0 for another under the same bulb), then flip them to 12/12 under the same conditions and measure the grams per watt output of each set. After all, that would be the ultimate goal anyway since the 24/0 advocates claim better production with that light cycle.

I think what most people are missing in this argument is this.....

Spurrs point is to give the plant the maximum amount of photons it can process, per day, for 18 hours. When you do as such, and let it rest for 6 hours, you will get maximum growth.

Now, when you DO NOT utilize maximum photon admission in those 18 hours, running 24/0 is more beneficial because the plant is basically starved for light and hasn't had enough light to store energy for night growth, which in turn makes 24/0 appear more beneficial.

Now, the proper way to test would to give two identically sized/strain/phenotype plants maximum photons (slightly short of saturation) per second, one plant for 18 hours, the other for 24.

This is when you will see 18/6 more successful than 24/0.
That is at least the way I understand what Spurr is saying, breaking it down to laymans terms of course.
If I'm missing something, I'm sure Spurr will set me straight.

 

[VerdantGreen]

seriously; i was willing to do a side by side
same room; same make of tents; same strain; same nutes; both fed off float valves from a similar reservoir in dwc; etc...

spurr told me i was full of shit and wasting my time because i wasn't measure ppfd

.....

hi opt1c, i have been following the thread and, whilst i agree that spurr is often rather opinionated and blunt, he didnt tell you that you were full of shit. (unless i missed something )

I agree, enough talk. There is no need to run side by sides because the jury is already in: plants like cananbis (C3) do better, and grow faster, with a dark cycle assuming enough DLI is provided in the day.

Also, side by sides without controlling all major factors that affect growth is a waste of time and proves nothing. To do a side by side that shows anything worthwhile you need to control and measure PPFD, PPFD-DLI, soil-water status (i.e. "water tension"), VPD, ADT, C02, etc., etc.

......

the thing is that spurr's assertions about plants growing better with a dark period are dependent on those plants receiving an optimum amount of light during the light cycle - so your offer of a side by side (which im sure lots of people would be interested in seeing) would not test what he is claiming unless you were able to measure the amount of light that the plants were receiving during their light cycle.

as for science versus traditional growing wisdom, i dont see why this site cant address both, as long as people are tolerant of each other.

cheers

VG

 

[opt1c]

phoenix without ppfd pictures and results don't mean anything; haven't you been listening to spurr

i mean two of the exact same lights with new bulbs one on 18 hours a day the other on 24; cuz same bulbs and brand means you aren't controlling those variables

from the sounds of it you don't even need plants to do a side by side just a PPFD sensor

 

[opt1c]

There is no need to run side by sides because the jury is already in: plants like cananbis (C3) do better, and grow faster, with a dark cycle assuming enough DLI is provided in the day.

Also, side by sides without controlling all major factors that affect growth is a waste of time and proves nothing. To do a side by side that shows anything worthwhile you need to control and measure PPFD, PPFD-DLI, soil-water status (i.e. "water tension"), VPD, ADT, C02, etc., etc.

i guess if i waste my time and prove nothing in my book i'm full of shit; but then again he thinks that soil is a good medium for scientific research

 

[The Phoenix]

I think what most people are missing in this argument is this.....

Spurrs point is to give the plant the maximum amount of photons it can process, per day, for 18 hours. When you do as such, and let it rest for 6 hours, you will get maximum growth.

Now, when you DO NOT utilize maximum photon admission in those 18 hours, running 24/0 is more beneficial because the plant is basically starved for light and hasn't had enough light to store energy for night growth, which in turn makes 24/0 appear more beneficial.

Now, the proper way to test would to give two identically sized/strain/phenotype plants maximum photons (slightly short of saturation) per second, one plant for 18 hours, the other for 24.

This is when you will see 18/6 more successful than 24/0.
That is at least the way I understand what Spurr is saying, breaking it down to laymans terms of course.
If I'm missing something, I'm sure Spurr will set me straight.

Well I obviously dont get what you are trying to say. The real world is putting sets of plants under a light source and getting the best grams per watt ratio you can get for the money your spending.

In my book it all comes down to grams per watt in the end, and if you can spend less money with 18/6 and maintain your GPW ratio then what else matters?

 

[macdiesel]

Well I obviously dont get what you are trying to say. The real world is putting sets of plants under a light source and getting the best grams per watt ratio you can get for the money your spending.

In my book it all comes down to grams per watt in the end, and if you can spend less money with 18/6 and maintain your GPW ratio then what else matters?

Verdant Greens post below mine said the same exact thing.

We're pretty much splitting hairs at this point.

 

[DHF]

I only wish that the old sites weren`t dead and gone because this very topic was SO determined many many yrs ago by the cream of the crop growers/breeders.......WITHOUT scientific studies done on crops regardless of their class compared to Pot.........

On the job training`s what we called it.....first hand knowledge....not published pdf`s bout maters and taters , regardless of plant class since no studies have been done specifically on the different varieties from one end of the spectrum to the other on marijuana from ruderalis , indica , sativa , and ALL their hybrids in between we deal with , breed , cross , and grow daily..............

Spurr/Gojo........I respect your knowledge , and we`re on the same page in that through my experience of indoor cultivation with MANY trials of 24/0 and 18/6 with different strains/varieties from full indica dominant through hybrids on through pure sativa`s , that they ALL behave differently under each vegtime parameter IME........

Indica`s fare better with the 24/7 process under T-5` stackin internodes and filling in while not growing vertically much if any after the flip to 12/12 all the way through end of stretch thus needing more concentrated light closer to em for the stacking process.......

Sativa dominant cuts will stretch their guts out 24/7 without a rest , thus employing 18/6 and even 16/8 would be in their favor for vertical growth control sooner than later huh ?............

That`s what I saw yrs ago trying to convert some of my best outdoor mexican "Sativa-zilla" varieties to indoor growing conditions without much success I might add............

Hybrids tend to hermie later on in their cycle more than not if not given the rest period through veg , but that`s only what I`ve observed first hand over many yrs , and could be different under other surroundings ......

18/6 makes sense for most of everything I`ve ever run in my rotations.........Indica dominant plants like Bubba are a whole different animal for production purposes........

I mean no disrespect to the science end of things that I never knew about that caused the effects I dealt with , but .......

It was unanimous from side by side trials waaaaay back in the day that 18/6 was the holy grail for end results from a true grower`s point of view running the same strains/varieties over and over come harvey..............

I used 400 watt Metal Halides for pre-veg back in the day , but when T-5`s were found and ableta get closer to the rooted cuts for internode stacking , it wasn`t rocket science till they went under the big lights in the bloom rooms for the end results.........

Phoenix.....Respect.....DHF...........

 

[The Phoenix]

Guys, it's really simple - let's use water filling a bucket (as was previously used) as an analogy.

Spurr is saying that to fill a five gallon bucket (aka, provide MAX DLI per day to the plant), your plant will respond better to a a hose running 5/18ths gallon/hour for 18 hours than a hose running 5/24ths of a gallon for 24 hours.

So, in order for a comparison test to be legit in his eyes, you must (using simple terms and an assumption or two) veg for 24 hours under a 400 and compare to vegging 18/6 under a 600, or whatever wattage of light you would need to provide the same DLI in 18 hours that the 400 provides in 24 hours.

Well thanks Bob, the answer to the problem is if you want to veg 18/6, then get a bigger bulb to get the desired results as the smaller one under 24/0.

Quite frankly, I think anyone can figure that out without any special test equipment and need for side by side experiments. 1kw bulbs and the sun with 18/6 light cycle absolutely destroy 400 watters at 24/0 with the same plants for example.

 

[spurr]

I am posting this now because I have to head out, but I may do slight edits to it later today

While I think a series of good side by side indoor grows with slow vegging indica clones from the same plant would be good, I see no need to go out and spend $200 for a meter if your test is side by side under the same bulb at equal distances dont you think spurr?

If the side by side is about 18/6 vs. 24/0, then yes, a quantum sensor needed. The reason is, to test 18/6 vs. 24/0, in terms of the most growth by hours of light per day, we need to make both DLIs equal (i.e. for 18/6 and 24/0). The DLI is the main variable that people are not considering, nor controlling. DLI matters much, much, much more than hours per day, thus if we don't equalize DLI the test isn't really about hours of daylength; it's about two different DLIs.

And if a grower uses a canopy smaller than a meter^2 they can use the quantum sensor to find the irradiance for a smaller area. Ex. umoles/foot^2/second instead of PPFD (i.e. umoles/meter^2/second). If a grower uses umoles/foot^2/second they can use that to find DLI of the smaller canopy.

To test 18/6 vs. 24/0, the grower should provide the same DLI for both daylengths. To do so, they need to adjust the PPFD, and to adjust the PPFD, they need to know the PPFD. For example, the PPFD for the 18/6 daylength needs to be higher than the PPFD for the 24/0 daylength in order to make both DLIs the same.

If a grower tests 18/6 vs. 24/0 and doesn't account for and equalize the most important light variable, DLI, the side by side is moot in terms of effect of hours per daylength. We must control the biggest variable to fastest plant growth: DLI. Once that is done, the test of 18/6 vs. 24/0 will be a real test of shorter day vs. longer day; and hence, be a test of the effect of dark cycle on cannabis growth.

If a grower doesn't account for and equalize DLI then the test of 18/6 vs. 24/0 is really a test of two different DLIs, not a test of two different daylengths.

Using a testing protocol I have described allows for analytical and truly useful results and would go far to advance cananbis science because so far I have found zero studies in academia looking at ideal DLI for cannabis; all studies are about ideal PPFD for cannabis. Of course, other factors need to be measured and controlled, most notably Air-to-Leaf Vapor Pressure Deficit (and VPD is cheap and easy to measure and control); also measuring Co2 is a great idea, but not strictly needed if the grower isn't injecting Co2...

Does that makes sense? I hope I am explaining it well enough.

FWIW:

Having a basic quantum sensor is well worth the money ($199). With a quantum sensor a grower can better adjust the light for ideal plant growth and waste less light in terms of under and over application of light intensity (irradiance).

Using a quantum sensor a grower can much more actuality calculate garden efficiency. Instead of using 'grams per kilowatt' a grower could use 'grams per 30-day DLI' (just as an example).

By using a quantum sensor a grower can test various light sources too, this would put an end to the LED vs. HID war in terms of light intensity (irradiance).

Using 'watts per square foot' to judge what lamp is good X sized canopy, or using Lumes or Lux to judge the better lamp (and lamp for X sized canopy), are all highly flawed. If one uses a quantum sensor all the flaws with those other uber poor methods are moot.

I assume when the like of J.Cervantes, E.Rosenthal, etc., first wrote about using a foot candle or lumen meters lots of growers balked; and suggested 'watts per square foot' is sufficient. Just like they do when I suggest using a quantum sensor instead of a food candle or lumen meter. In the near future, I assume 5-10 years, I think quantum sensors will be a fairly standard tool for growers just like a foot candle or lumen meter is today...

I look at it like this: many growers will plunk down hundreds of dollars fro Co2 injection because it can increase yield and growth rate. They don't mind the cost because the benefit is so great (cost:benefit ratio). Likewise, using a quantum sensor to provide ideal DLI and PPFD allows for highest rate of photosynthesis, and highest net rate of photosynthesis, and highest Co2 fixation, and highest yield, etc. All of those factors mean fastest growth and biggest yields (that has been proven already). Using Co2 injection without using ideal irradiance (as PPFD and DLI) means a grower is not getting the most benefit from Co2 because under ideal PPFD and DLI, the plant uses Co2 most effectively and efficiently.

I think the big problem is most growers do not realize the great befits they can reap from using a quantum sensor (e.g. faster growth while using a dark period, higher yields, greater Co2 fixation, better assimilate and partitioning, etc, etc.). The other big problem is that most growers are completely unaware of quantum sensors, even though they have been used in commercial horticulture for decades, and by plant biologists for even longer.

I am trying to get the word out about quantum sensors, why we should use them, and what they can offer a grower...admittedly I am fighting an uphill battle

In the end, a grower who isn't willing to spend a mere $199 for the latest in plant light science just doesn't understand the benefits. Most people will spend $199 on bull-crap in one month, like going to bars, junk food, movies, video games, girl friend/boy friend, etc., why not just save up some money for a month or two and spend it more wisely? And any commercial grower who isn't willing to spend $199 shouldn't be a commercial grower, IMHO.

Other, better options for quantum sensors than the one from SpecMeter:

1. The other inexpensive quantum sensor I would suggest to growers is from Apogee, it's $299 and is model MQ-100. That quantum sensor and data reader (in one) is much better than the SpecMeter quantum sensor because it has cosine-corrected head (thus it provides a more even unweighted reading over the blue PAR range) and it has a domed diffusion disk. For an extra $100, vs. the SpecMeter the Apogee is a deal! And Apogee is a better company than SpecMeter...

2. Commercial growers should really spend extra cash to get one of the best quantum sensors (for under a few thousand dollars) from Li-Cor. The Li-190SA ($380), or Li-191SA ($1,750) and data reader Li-250A ($675) or data logger Li-1400 ($1,695) from Li-Cor. Li-cor quantum sensors are much better than the SpecMeter and Apogee quantum sensor and the Apogee is much better than the SpecMeter. The Li-190SA and Li-250A costs about $1,050 together. The Li-191 and Li-250A costs about $2,400 together.

The big difference between the Li-190SA and the Li-191SA is the Li-190SA is a single sensor, and the Li-191SA is a 3' long rod with 10 quantum sensors in it, and it automatically adds up each datum from all 10 sensors then averages them and provides a single figure for irradiance over 3'.

3. Using the Li-Cor Li-190SA, or Apogee MQ-100 or SpecMeter FieldScout a grower would need to take many readings to find the irradiance over X area. Ex. for PPFD (umols/meter^2/second) the grower should take measurements every 3", thus 144 measurements, add them up and find average to find PPFD. Or for a smaller area, ex. umoles/foot^2/second the grower would again take readings every 3", add them and find the average to find the instantaneous irradiance over a foot^2.

Using the Li-Cor Li-191SA a grower would take many less readings. For PPFD they would take 12 readings (every 3" width-wise) add them up and find the average for PPFD. Using the Li-190SA, MQ-100, or FieldScout is the better then the Li-191SA, albeit more laborious option, because they provide much more versatility and fine-grained detail.

I plan to use the Li-190SA to re-do testing of reflectors that Pico has done in this thread using a lux meter. Using a quantum sensor the readings will be much more accurate. Pico did a very great job with his thread, esp. the graphs, etc., but I think using a quantum senor would make this work that much better (link)

Lets say you drop the sets of clones from a few plants under under the bulb and pull out one set into darkness for 6 hours everyday. Wouldn't that take the variable out of having two bulbs light output affecting the experiment and eliminate the need to purchase that sensor?

No, because you would not be giving the same DLI to both sets of clones. Thus the test would be about two different DLIs, not two different daylengths.

I think a better measurement of effectiveness for an experiment also might be to take the same sets of clones, and give them equal veg time (18/6 for one set and 24/0 for another under the same bulb), then flip them to 12/12 under the same conditions and measure the grams per watt output of each set. After all, that would be the ultimate goal anyway since the 24/0 advocates claim better production with that light cycle.

I agree, with the caveat that during 18/6 vs. 24/0 both sets of clones get the same DLI. And they get the same DLI under 12/12 because age of lamp will affect PPFD, and thus DLI.

Also, if using a quantum sensor we could measure weight by 'grams per 30-day DLI', or 'grams per DLI', or 'grams per PPFD', etc., all of which are better than 'grams per watt'. FWIW, using 'grams per kilowatt' is much better than 'grams per watt' (because 'grams per watt' doesn't take time into account).

FWIW, when using weight as a measurement it's very important to subtract the moisture content (i.e. water weight) from the buds to get a true value of the dry bud weight; there is no sense in including water weight with bud weight when testing.


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The best way to really test for ideal PPFD, DLI and hours of light per day, is measuring rate of photosynthesis (Pn) to find the PPFD and DLI and hours per day that provides high Pn and highest Pnnet (sum Pn over a whole day). Then, a grower can know for sure they are giving their plants the best possible light for highest yield and fastest growth. A photosynthesis meter (to measure CO2/O2 fixation/respiration, chlorophyll fluorescence, transpiration, stomatal conductance, PFPD, etc.) costs about $20-40k depending upon features and manufacture. However, a really, really good option for most growers (and what I plan to use until I plunk down $20-40K) is a "chlorophyll fluorometer", such as the EARS-PPM300 (~$7,000), or the Walz PAM-2500. Using chlorophyll (Chl) fluorometry a grower can measure rate of photosynthesis well, and cheaply (vs. using a Pn meter). And Chl fluorometry also shows when a plant is experiencing photosynthesis inhibition from too much PPFD (ex. "midday depression of photosynthesis") or too much DLI. Not only that, but when using Chl fluorometry a grower can judge the health of the plant, etc. Here are some great links about using a the EARS-PPM300 to test Pn and photoinhibition: "Preventing Light Damage", "Fluorescence and photosynthesis", "Measuring fluorescence and photosynthesis".

 

[spurr]

Guys, it's really simple - let's use water filling a bucket (as was previously used) as an analogy.

Spurr is saying that to fill a five gallon bucket (aka, provide MAX DLI per day to the plant), your plant will respond better to a a hose running 5/18ths gallon/hour for 18 hours than a hose running 5/24ths of a gallon for 24 hours.

Yes, except the better response comes from the night period because the DLI will be the same with both daylenghts.

So, in order for a comparison test to be legit in his eyes, you must (using simple terms and an assumption or two) veg for 24 hours under a 400 and compare to vegging 18/6 under a 600, or whatever wattage of light you would need to provide the same DLI in 18 hours that the 400 provides in 24 hours.

Yes, but you also have to measure PPDF to find DLI, a grower can't use more watts and assume it's the same DLI.

And if a grower uses a canopy smaller than a meter^2 they can use the quantum sensor to find the irradiance for a smaller area. Ex. umoles/foot^2/second instead of PPFD (i.e. umoles/meter^2/second). If a grower uses umoles/foot^2/second they can use that to find DLI of the smaller canopy.

Thanks Bob, that was a very nice and friendly post, and well written too, maybe we can let bygones be bygones?