Cannabis Daily Light Integral

Randomblame said:

Look at this journal, bro!
He tried to use as much light as possible using 8 QBv2 and he also added 1500ppm CO2 to max out light usage. More than 1050μMol/s/m² for 12h was impossible without harming the plants. Most info are in the first 10 pages and the whole thread has 28 pages or so currently.

https://www.rollitup.org/p/14607471/

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One would also have to expect that "Light Quality" also plays a huge role in max tolerable DLI
Those pesky photons outside of the 400-700nm range

"To add some perspective, the highest DLI recordings in the USA are in the Californian desert at 45 DLI. These measurements relate to the Photosynthetically Active Radiance (PAR) of the solar light-wave, which is between 400nm and 700nm."

https://www.lightrail3.com/the-science-of-lightrail/

OneHitDone said:

One would also have to expect that "Light Quality" also plays a huge role in max tolerable DLI
Those pesky photons outside of the 400-700nm range

"To add some perspective, the highest DLI recordings in the USA are in the Californian desert at 45 DLI. These measurements relate to the Photosynthetically Active Radiance (PAR) of the solar light-wave, which is between 400nm and 700nm."

https://www.lightrail3.com/the-science-of-lightrail/

Click to expand...

I've got a friend who's working on a commercial lighting product - he insists that you can produce a light that has more usable PAR for MJ if you make sure you don't have too much green (500-600nm) in your spectrum.... so, he's targeting a usable 1000 PPFD but also < 5000 FC (or 50K lux). I'm not saying he's right, but he may be on to something.

caretak3r said:

my end game is to try 1.5 hr on/ 10.5 hr off, driving as much light intensity as possible, technically that would 3 hrs of high intensity light in a 24hr period which doesn't seem too bad....

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With only 1,5-3h light it should be possible to give them much more but above 1500 or 2000 you need a lot of distance between boards and canopy( 24" at least) to avoid bleeching. That means you would need ~1000w inside a 4x 4' tent to reach 2000μMol/s/m² with a distance of 24inch.

OneHitDone said:

One would also have to expect that "Light Quality" also plays a huge role in max tolerable DLI
Those pesky photons outside of the 400-700nm range

"To add some perspective, the highest DLI recordings in the USA are in the Californian desert at 45 DLI. These measurements relate to the Photosynthetically Active Radiance (PAR) of the solar light-wave, which is between 400nm and 700nm."

https://www.lightrail3.com/the-science-of-lightrail/

Click to expand...

Yepp, but sunlight isn't constant 1500μMol/s for the whole day. But I agree the wavelength outside the PAR range has a huge effect; far-red for instance helps to even out the difference between the two photosyntesis systems.
The "PAR range" will soon get a new DIN and will change to the 380-780nm range.

Randomblame said:

With only 1,5-3h light it should be possible to give them much more but above 1500 or 2000 you need a lot of distance between boards and canopy( 24" at least) to avoid bleeching. That means you would need ~1000w inside a 4x 4' tent to reach 2000μMol/s/m² with a distance of 24inch.

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thanks, I was looking for this type of info.... can you expand on why the need for 24"? would it matter if I was using strip lighting vs cobs? I'm wanting to push the boundaries in a tote/tub grow with an abundance of airflow (110CFM in 5 square ft of tote space). I'm using a panasonic whisper exhaust fan and taking advantage of using the the air intake to cool the lighting at the same time. Pic of me testing the efficacy of using intake to cool the cobs - works well.... I have lots of strip lighting I could use instead, or supplement with.

caretak3r said:

thanks, I was looking for this type of info.... can you expand on why the need for 24"? would it matter if I was using strip lighting vs cobs? I'm wanting to push the boundaries in a tote/tub grow with an abundance of airflow (110CFM in 5 square ft of tote space). I'm using a panasonic whisper exhaust fan and taking advantage of using the the air intake to cool the lighting at the same time. Pic of me testing the efficacy of using intake to cool the cobs - works well.... I have lots of strip lighting I could use instead, or supplement with.View attachment 4240087

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Loving the Kapton tape, use it myself now n again.

Moflow said:

Loving the Kapton tape, use it myself now n again.

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-- I'm prototyping, don't want anything set in stone

Randomblame said:

Look at this journal, bro!
He tried to use as much light as possible using 8 QBv2 and he also added 1500ppm CO2 to max out light usage. More than 1050μMol/s/m² for 12h was impossible without harming the plants. Most info are in the first 10 pages and the whole thread has 28 pages or so currently.

https://www.rollitup.org/p/14607471/

Click to expand...

Sorry to say, but that guy is an idiot and otherwise highly unreliable though. Wouldn't really accept his anecdotal evidence. There are plenty people who use high PPFD values to good effect. Tried it myself too plants exploded and tops were much bigger and more compact. You do need to get everything more ore less right though. Including climate and nutrients. it's not just a matter of cranking up the lights.

dunno, if you have the lights, why not use some of them for sidelighting instead?

sethimus said:

dunno, if you have the lights, why not use some of them for sidelighting instead?

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not sure if this was directed at me, but if so, in my main tent, i have 6 X 4ft 2nd gen EB strips for sidelighting. My questions and postings today here are just about an experiment I'm setting up.

I followed the thread and can not say he did something wrong and for sure he has not simply cranked up the light. VPD, CO², nutes and all that variables were in check. And for the 2 strains used it was the maximum intensity ..

@caretak3r
2000μMol/s of light means a lot of heat and energy radiation so mabe it works with enough airflow/cooling. I've not tried it with such high intensity. I've only tried to use ~1200μMol/s from COB's at 6-8" above the plants and in my small 9sft area it was impossible. The air dried out too much and had constantly a too high VPD. With a hydro system it would probably have been more possible with a lower nute strength but they stood in super soil with relatively high EC.
But yea, this was with 12h the day not only 3h. The only way to figure out if it works or not is to try it and see what happens. My thumbs are pressed! I like the unconventional approach..!

1000µmol over double the size > 2000µmol over half the size

After over two years I asked the guy and he says the 1120w LED array outperforms what he was getting from the 2x 600w HIDs. He also mentioned that it lowers the cooling cost a notable amount. I would say this is because the LEDs radiate heat up and the convection system changes the average temp at his thermostat, but he has a double chamber system scrubbing the air as it circulates so air convection should be the same. It doesn't make sense to me that an 80w drop in power has a notable effect on cooling but he swears it does.

Rahz said:

After over two years I asked the guy and he says the 1120w LED array outperforms what he was getting from the 2x 600w HIDs. He also mentioned that it lowers the cooling cost a notable amount. I would say this is because the LEDs radiate heat up and the convection system changes the average temp at his thermostat, but he has a double chamber system scrubbing the air as it circulates so air convection should be the same. It doesn't make sense to me that an 80w drop in power has a notable effect on cooling but he swears it does.

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I suspect it has something to do with the fact that LED emits less infrared and plants transpire more, which reduces cooling requirements.

One would think it's a simple Watts to Watts comparison but it doesn't seem to work that way in practice.

curious readings...




...curious DLI chart similar VPD charts...












more info in other post...https://www.rollitup.org/t/looking-for-meijiu-a8-650w-reviews.1036226/post-16185283

en temas de VPD...

...y es el porque añado un BMP390L...al mix de sensores...SHT41 + SCD41 + BMP390L + BME280 + Nano Lambda + SMT32 + ESP32 + raspi CM4...+..... PT1000 (sonda para temperartura de liquidos...principalmente...capacitive Soil moisture sensors... Special Cams to sense or monitor plants....etc...
....la luz y el co2 los tendre bien sensados....tambien para temas de VPD...

pensaba extenderme con mas info en ingles ...pero este post no le gusto a nadie...una pena...

e function actived.... aunque no se si me dara tiempo.... este no creo lo borre yo...

Paz y Amor...en 2021 aun mucho mas...

Saludos desde Tenerife

more curious readings...








EX....
You are growing cucumbers and want to give them around 25 DLI.
Your grow light produces 500 PPFD at 18" from the plant according to your grow light PPFD map/light footprint.
If the lamp's distance is increased to 20" from the plant, it produces 400 PPFD at the canopy.
If the lamp is lowered to 15", it produces 700 PPFD.

By looking at the chart we see that
~25 DLI is achieved by exposing the plant to 500 PPFD over 14 hours
but also when exposing the plant to 400 PPFD over 17 hours or 700 PPFD over 10 hours.

Choose a combination that fits both your grow set up but also your plant's minimum and maximum PPFD limits.
Very high PPFD levels over a short duration of time or very low PPFD levels over a long duration of time are rarely ideal for good growth......


bad day to me.... (some bad news...on covid theme)...maybe a bit change on info... change something today on me...






better...or maybe better...other day...

no ...mejor cambiar hoy...ehhh Wilson...cambia musikita ....pasa a la de baile...toca entrenamiento...vamossss pisstaaa...

bufff much better...

gracias por el like bro Mo... jalll...tengo visita...hasta dentro de un rato...que te pondre mas info...

...bueno ya estamos por aqui...gracias por el amor bro Os... añadiendo info...












too curious sistem Wilson...yo le pondria ruedas con freno...a mi mujer le gusta mover los muebles para barrer y fregar...y algo se me pega...yo prefiero ponerle ruedas a los muebles...

Paz y Amor...en 2021 aun mucho mas...

Saludos desde Tenerife - Islas Canarias