PPFD Measurements & Analysis for LEDs

[ConstantGreen]

re: PPFD Measurements & Analysis for LEDs

Hey folks, new here, got a question,
I know Lux and lumans and LEDs mean nothing in measuring sense, but what if,

You have 1000 par, but 500 lux? Does it matter that the intensity is so weak? as per Lux measurement? Ive seen Neils vidoes (BlackDiamond) and he talks about 60,000 lux, but at 60,000 lux, what if Par is 1400? For Lux not meaning much, why does a LED light builder talk so much about it?

Not sure why he talks about lux but it's not as precise as PAR for measuring grow light quality. Lux is a measurement of light visible to the human eye. PAR is a more specific range(400-700nm) within the visible light spectrum that plants use to grow. A lower or higher lux value doesn't matter, it's PAR that counts.

600 par but 100 lux, would mean what? What could one expect from these hypothetical numbers? Does intensity ( lux) mean penetration force?

That doesn't mean anything exactly, but it probably means the light source is deep red or deep blue. Reds and blues are harder for humans to see so they aren't worth many lux, but plants love red and blue light so it's worth a lot of PAR to them. Humans see green light the brightest, so green is worth the most lux, but plants do not absorb green light so well. So a green LED might give more lux than PAR. Lux alone doesn't tell you anything about penetration unless you measure it at multiple heights.

What if all flowers are on the surface, and need little penetration because of it?

Having all flowers on the surface in a flat canopy would be ideal. It limits your needs for penetration. But this is something I don't quite understand and want to learn more about too.

Brain picking, since par and Lux are worlds apart in the LED Land.

Thanks,

Hello and welcome to 420 Mag! Replied to your questions individually in the quote.

My question is... say the maximum photosynthetic rate for cannabis is 1500 PPFD with CO2. I'm pretty sure that study was done on single fan leaves, not whole plants. So does every leaf on the plant from top to bottom need to be radiated at 1500 PPFD to achieve maximum results? If so, penetration would be pretty important, to make sure those bottom branches are getting just as much light as the top branches. But it seems almost impossible to max out that way, you would need lights all around the sides and within the canopy.

I've had canopies so dense... there's no way light from the top can squeeze through more than 6 inches of dense foliage. So that raises the question of how deep should a packed canopy be. Or whether it should even be flat and dense.

 

[Mayne]

re: PPFD Measurements & Analysis for LEDs

Hello and welcome to 420 Mag! Replied to your questions individually in the quote.

My question is... say the maximum photosynthetic rate for cannabis is 1500 PPFD with CO2. I'm pretty sure that study was done on single fan leaves, not whole plants. So does every leaf on the plant from top to bottom need to be radiated at 1500 PPFD to achieve maximum results? If so, penetration would be pretty important, to make sure those bottom branches are getting just as much light as the top branches. But it seems almost impossible to max out that way, you would need lights all around the sides and within the canopy.

I've had canopies so dense... there's no way light from the top can squeeze through more than 6 inches of dense foliage. So that raises the question of how deep should a packed canopy be. Or whether it should even be flat and dense.

Great reply Versai, i see now a bit better.

Here is another one for ya.

Why would a 120 LED panel have just 1 or 2 IR LEDS,?? I would assume because its because the light takes more energy from the plant to eat or "Cool", since IR and UV are hotter, and put more beating on the plant. but you have to think, maybe a 3rd of the plant is getting those waves of light at the time its on. So, does the entire plant benefit from exposure from light from just a fraction of the plant? Or, just those leaves that are capturing the Waves themselves? So, what would be the actual benefit to even have them?

What got thinking about this is, you can literally keep a plant in veg by exposing 1 single leaf to light past 12 hours, with just 23 watts of 3500K.

That is all in reference to the power of the " Leaf" as we were talking about above.

So, we can understand, PAR is NOT penetration, but simply color showering on a leaf at any given time. No Force, just light falling. So how can we figure out intensity? If LUX means little, other then intensity reading, which is intune of penetrational factors, how do we figure it all out?

 

[Mayne]

re: PPFD Measurements & Analysis for LEDs

I think I figured it out. Also want to add, this is relevant to this thread, as this is Mars 300 talk and PAR.

OK, added Lenses to mars300, at 18inches its 1400 PAR, and 55,000 lux, 5,100 FC, 54,895.943 Lumans PSM, but footprint is 8 inches basically. And like you said above, More reds and Blues in Mars spectrum, and not enough white, like Neil has said as to why his lights are better for penetration, AH HA. Love watching his videos, learned soooo much.

No PAR meter to take readings from further distances, so

@ 24 inches, 35,000 lux, 3,000FC, 32291.73 lumans PSM PAR??

100,000 lux @ 10inchs

There are 2 of these setup, with 120degree lenses, 2x2-- bracketed end to end 2 inch gap, with 1 inch center pitch, To better the angle to the center more.

Idea, Add more white, and going to do a experiment with diffusion using Solexx Poly Panel 3.5MM.. Say 30% better plant absorption, and will breakup and scatter the FOCUSED Waves of the spectrum, and mix them more consistently before hitting the leaf surface. 95% of PAR is kept. The "penetration" is horrible with Mars300

Id have to imagine, PAR still has to be above 900 at 24" so even diffused, still have more then 800, and much much better blend of the spectrum distribution.

about to get a PAR meter to.

I think Diffusion is the missing link to a great LED,

 

[ConstantGreen]

re: PPFD Measurements & Analysis for LEDs

Great reply Versai, i see now a bit better.

Here is another one for ya.

Why would a 120 LED panel have just 1 or 2 IR LEDS,?? I would assume because its because the light takes more energy from the plant to eat or "Cool", since IR and UV are hotter, and put more beating on the plant. but you have to think, maybe a 3rd of the plant is getting those waves of light at the time its on. So, does the entire plant benefit from exposure from light from just a fraction of the plant? Or, just those leaves that are capturing the Waves themselves? So, what would be the actual benefit to even have them?

What got thinking about this is, you can literally keep a plant in veg by exposing 1 single leaf to light past 12 hours, with just 23 watts of 3500K.

That is all in reference to the power of the " Leaf" as we were talking about above.

So, we can understand, PAR is NOT penetration, but simply color showering on a leaf at any given time. No Force, just light falling. So how can we figure out intensity? If LUX means little, other then intensity reading, which is intune of penetrational factors, how do we figure it all out?

Those are some good questions that I don't have answers to. While plants use primarily use 400-700nm for photosynthesis, and chlorophyll gets peak responses from blue and red, you wouldn't want a panel with just blues and reds. The other colors between blue and red still play a role, as well as infrared and UV. PAR meters alone can't account for the spectral quality of a LED panel and the ratios of IR:Blues:Reds:Etc, but it's becoming more accepted that plants enjoy a full-spectrum. Engineers and growers more advanced than myself are using spectroradiometers that account for the small differences in PAR value that one nm has over another. But I think the perfect spectrum is still up for debate.

Yes, think of PAR light as a rain shower. Quoting this example from another forum:

Think of light as rain and the light fixture as a cloud.

PPF tells us how many raindrops are falling from a cloud every second.

Let’s assume that cloud produces one million raindrops per second. If it is a large cloud the size of the state of Texas, you probably wouldn’t even know it was raining outside. But, if the cloud was the size of a car, you would probably want to put on a life vest if you were directly under this cloud! The raindrop density (PPFD) from the car-sized cloud in the second scenario would be very apparent to the unfortunate person under it. It is the same scenario with lighting systems. PPF tells us how many photons are being produced by a lighting fixture every second, but it doesn’t tell us where the photons are landing. That’s why we need PPF-Density or PPFD.

 

[Mars Hydro]

re: PPFD Measurements & Analysis for LEDs

thanks,sometimes i just can not explain everything in a right way,but i will try my best.
I asked our engineer to test PPFD for all of our lights,but they need a little time,it's a lot work for them.
We will try our best to offer everything which our customer needed.

Thanks for supplying the chart, that is the great customer service people want to see. Would have been A+ if you also thanked the OP for feedback and just posted the chart straight up.