What is my PPFD?

testiclees said:

My lamp is approx 240 par watt ( 4 x 3490 & 4 x v29)
My space is 50" x 24" = 1200"sq
1200"sq =8.3'sq.
240 par W / 8.3'sq. = 28.8 par W sq ft
28.8 x 45 = 1296ppfd If this is correct I would likely benefit from a further increase in the clearance.

Is the metric conversion accounted for by the 4.5 vs 4.7 conversion factor?

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Let's figure this one out:

1.) PAR W = ~240W

2.) Targeted Area = [(50" x 1' / 12")*(24" x 1' /12")] = ~8.33 square feet = 0.774 square meters

3.) PPF = [(240 PAR W) * (4.70 umol/J) = 1128 umol

^^^^ the 4.70 was arbitrary, as I don't know which temperatures you're running with your Vero 29s and CXB3590s

4.) PPFD = PPF / Targeted Space = 1128 umol / 0.774 square meters = ~1458 PPFD (gross, not net)

Conclusion: A great PPFD number to have for flowering, depending on distance between light sources and plants.

AquariusPanta said:

Let's figure this one out:

1.) PAR W = ~240W

2.) Targeted Area = [(50" x 1' / 12")*(24" x 1' /12")] = ~8.33 square feet = 0.774 square meters

3.) PPF = [(240 PAR W) * (4.70 umol/J) = 1128 umol

^^^^ the 4.70 was arbitrary, as I don't know which temperatures you're running with your Vero 29s and CXB3590s

4.) PPFD = PPF / Targeted Space = 1128 umol / 0.774 square meters = ~1458 PPFD (gross, not net)

Conclusion: A great PPFD number to have for flowering, depending on distance between light sources and plants.

Click to expand...

Thank you very much. Seems Ive been overly heavy on the photons. With this learning I expect nice improvements. For the current group I'm going to use risers to even out the canopy and test clearance at *20" and 24"

*

AquariusPanta said:

Let's figure this one out:

1.) PAR W = ~240W

2.) Targeted Area = [(50" x 1' / 12")*(24" x 1' /12")] = ~8.33 square feet = 0.774 square meters

3.) PPF = [(240 PAR W) * (4.70 umol/J) = 1128 umol

^^^^ the 4.70 was arbitrary, as I don't know which temperatures you're running with your Vero 29s and CXB3590s

4.) PPFD = PPF / Targeted Space = 1128 umol / 0.774 square meters = ~1458 PPFD (gross, not net)

Conclusion: A great PPFD number to have for flowering, depending on distance between light sources and plants.

Click to expand...

Hey AP when you say "depending on distance between light sources and plants" what would your thoughts be on best clearance in these conditions?

Thanks for your thoughts.

Wow thank you for this reminder !

But now i'm scared : i have 2000 PPFD (12x cxb3590 @1050mA on 0.54m²) !

So i have to remove some Cobs :/ ? Or i increase the distance with the canopy ?

I'd say double (or even triple) your grow space ..

That's way to much light for that space = plants can't use it = wasted money+energy = useless pollution.

Kiss92 said:

Wow thank you for this reminder !

But now i'm scared : i have 2000 PPFD (12x cxb3590 @1050mA on 0.54m²) !

So i have to remove some Cobs :/ ? Or i increase the distance with the canopy ?

Click to expand...

So what is the ideal range of ppfd one should strive for in a square foot when building or buying leds?

Kiss92 said:

Wow thank you for this reminder !

But now i'm scared : i have 2000 PPFD (12x cxb3590 @1050mA on 0.54m²) !

So i have to remove some Cobs :/ ? Or i increase the distance with the canopy ?

Click to expand...

You can see yield increases right up to 1500, but probably not huge gains between 1200 and 1500. If you don't want to expand your grow space you can always dim the lamp down to your desired PPFD and save some juice. Many people like the 800-900 range... excellent yield per sq/ft while still easy on the plants. A commercial grow is going to aim for 650 to maximize their yield per watt but anywhere between 800-1200 would be good for maximizing yield per sq/ft.

EfficientWatt said:

Hi,

Well PPFD is metric, so you have to convert to square meters at some point.

600W@56% efficiency => 336 PAR W

336*4.65 = 1562 PPF
10% reflection loss => 1562 * 0.9 => 1406 PPF

5' x 5' is ~2.25m²

1406 / 2.25 => Roughly 625 PPFD

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I have always been confused as where does the "4.65" (GreenGeens, 4.66) come from and does it depend on which COB you are using (2500K, 3000k, etc.)?

Thanks in advance.

In short, it's the conversion factor to go from PAR W => PPF (Photosynthetic Photon Flux).

Yes, it's dependent on spectrum/light source, as the amount of energy to make a photon varies depending on it's color/frequency.
(1 PAR W of blue light yields significantly less photons than 1 PAR W of red light.)

Organic Miner said:

I have always been confused as where does the "4.65" (GreenGeens, 4.66) come from and does it depend on which COB you are using (2500K, 3000k, etc.)?

Thanks in advance.

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Ok well i have tried many times to works these numbers and i am just not sure i am getting it right would love a little help.
I keep getting mixed up numbers for my ppfd.
my specs
4 x vero 29@ 1050 - 3000k
4 x vero 29@ 1400 - 2x3000k-2x4000k (have no clue if thats needed or not i just try to copy your guys/gals math formula)
All in a 2 x 4 tent.

So far what i can work out i am getting around 730 ppfd could one of the math master confirm this pls and thank you so much. (ps if it wasnt for supra rahz,greengenes,stardustsailor and many many more on here, for me being able to build my vero lights. Thanks to all even when some cant get along truly great stuff from all )