What is my PPFD?

Snaddehat

Well-Known Member
As title says... This might be simple enough to calculate, but since i'm completely useless when it comes to math, i'd appreciate a little help from the very knowledgeable people here :)
Tent size is 60x60x150cm, I'm running 4x CXB3590 (36v) 3000k 80CRI @ 1400ma, so 50-ish watt pr. COB. 1 driver pr. COB and drivers are 87% efficient. No lenses or reflectors. Light is hanging 40cm above canopy.
I hope that's all you guys need to help me here
Thanks in advance!
 

EfficientWatt

Well-Known Member
Which bin are those 3000K ?

I'll assume CB .. using Supra's numbers and method, roughly gives :

60x60 = 0.36 m²
200W@51% efficiency = 102 PAR watts
102 PAR W x 4.66 = 475 PPF

Accounting for 10% reflection losses = ~428 PPF

428 PPF / 0.36 m² = 1320 PPFD

That's a very high intensity, getting close to light saturation point.
 

Snaddehat

Well-Known Member
Thanks mate!
Damn... i knew i forgot something lol, yea it's CB :) and yes, i figured it would be close to saturation. So far so good though. I might try and get a MW driver @ 1050ma for next run to lower intensity a little and gain a little efficiency.
Thanks again for the calculation :)
 

Greengenes707

Well-Known Member
About 1290µmols/m^2/sec is what your canopy is experiencing. Before realworld taxes(walls, reflectors, lenses, zippers, seams, dust...you get it).

49wx4=196w
196 x 51%=99.96radiant watts
99.96radiant watts x 4.67µmols= 466.81
466.81÷.36m^2 =1296.7µmols/m^2/sec

Plenty of light. But not too much despite what you might hear. And will guarantee you max your space. Or have power to expand a little down the line. Plus you can always dim it.

What you will need to do to accommodate that much light is to adjust its relative intensity by adjusting the clearance/height. 40cm is too low for that much light. No matter how high you hang it in the tent with that much light, you should actually notice the best performance with the most clearance as opposed to very close or even at what is considered high normally.



http://biology.mcgill.ca/Phytotron/LightWkshp1994/1.5 Bugbee/Bugbee text.htm
CONCLUSIONS
Differences in radiation quality from the six most common electric lamps have little effect on photosynthetic rate. Radiation quality primarily alters growth because of changes in branching or internode elongation, which change radiation absorption. Growth and yield in wheat appear to be insensitive to radiation quality. Growth and yield in soybeans can be slightly increased under high pressure sodium lamps compared to metal halide lamps, in spite of greatly reduced chlorophyll concentrations under HPS lamps. Daily integrated photosynthetic photon flux (mol m-2 d-1) most directly determines leaf anatomy and growth. Photosynthetic photon flux levels of 800 μmol m-2 s-1 are adequate to simulate field daily-integrated PPF levels for both short and long day plants, but plant canopies can benefit from much higher PPF levels.
 

Snaddehat

Well-Known Member
Thanks GG, much appreciated input :)
I might be able to get the lights to 50cm above canopy, but beyond that my carbon filter is in the way...
We'll see how it goes... Week 4 of flowering starts tomorrow
 

john0000

Well-Known Member
Which bin are those 3000K ?

I'll assume CB .. using Supra's numbers and method, roughly gives :

60x60 = 0.36 m²
200W@51% efficiency = 102 PAR watts
102 PAR W x 4.66 = 475 PPF

Accounting for 10% reflection losses = ~428 PPF

428 PPF / 0.36 m² = 1320 PPFD

That's a very high intensity, getting close to light saturation point.
Which bin are those 3000K ?

I'll assume CB .. using Supra's numbers and method, roughly gives :

60x60 = 0.36 m²
200W@51% efficiency = 102 PAR watts
102 PAR W x 4.66 = 475 PPF

Accounting for 10% reflection losses = ~428 PPF

428 PPF / 0.36 m² = 1320 PPFD

That's a very high intensity, getting close to light saturation point.
hey can you post a formula for feet...by any chance ..im doing 12 cxb 3590 cd 3500k..4 each on a hog 185h c1400a,,in a 5ft by 5ft with height of 7 ft..80 degree glass lens..20 in above canopy
 

john0000

Well-Known Member
About 1290µmols/m^2/sec is what your canopy is experiencing. Before realworld taxes(walls, reflectors, lenses, zippers, seams, dust...you get it).

49wx4=196w
196 x 51%=99.96radiant watts
99.96radiant watts x 4.67µmols= 466.81
466.81÷.36m^2 =1296.7µmols/m^2/sec

Plenty of light. But not too much despite what you might hear. And will guarantee you max your space. Or have power to expand a little down the line. Plus you can always dim it.

What you will need to do to accommodate that much light is to adjust its relative intensity by adjusting the clearance/height. 40cm is too low for that much light. No matter how high you hang it in the tent with that much light, you should actually notice the best performance with the most clearance as opposed to very close or even at what is considered high normally.



http://biology.mcgill.ca/Phytotron/LightWkshp1994/1.5 Bugbee/Bugbee text.htm
CONCLUSIONS
Differences in radiation quality from the six most common electric lamps have little effect on photosynthetic rate. Radiation quality primarily alters growth because of changes in branching or internode elongation, which change radiation absorption. Growth and yield in wheat appear to be insensitive to radiation quality. Growth and yield in soybeans can be slightly increased under high pressure sodium lamps compared to metal halide lamps, in spite of greatly reduced chlorophyll concentrations under HPS lamps. Daily integrated photosynthetic photon flux (mol m-2 d-1) most directly determines leaf anatomy and growth. Photosynthetic photon flux levels of 800 μmol m-2 s-1 are adequate to simulate field daily-integrated PPF levels for both short and long day plants, but plant canopies can benefit from much higher PPF levels.
hey can you post a formula for feet...by any chance ..im doing 12 cxb 3590 cd 3500k..4 each on a hog 185h c1400a,,in a 5ft by 5ft with height of 7 ft..80 degree glass lens..20in above canopy
 

EfficientWatt

Well-Known Member
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
 

john0000

Well-Known Member
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
thank you and that is low right??
 

EfficientWatt

Well-Known Member
Good enough to grow, and possibly ideal if you're going for yield/W over bestest quality ..

A little more headspace is always appreciable tho, even if you don't use it.
Me, I'm shooting for 700-750 range, some go crazy and go well over 1000ppfd, gives great bud quality, sacrificing a little yield/W

I beleive @captainmorgan has been using less than that, with great results ... but he seems like a damn good and experienced grower .. very good space and canopy management in his grows from what I see.
 

john0000

Well-Known Member
Good enough to grow, and possibly ideal if you're going for yield/W over bestest quality ..

A little more headspace is always appreciable tho, even if you don't use it.
Me, I'm shooting for 700-750 range, some go crazy and go well over 1000ppfd, gives great bud quality, sacrificing a little yield/W

I beleive @captainmorgan has been using less than that, with great results ... but he seems like a damn good and experienced grower .. very good space and canopy management in his grows from what I see.
ok cool thanks..guess i should have went with the 15 cxb 3590 and the hlg 240 instead
 

testiclees

Well-Known Member
I think I too may be screwing up with too much light too close Re: @Greengenes707

"What you will need to do to accommodate that much light is to adjust its relative intensity by adjusting the clearance/height. 40cm is too low for that much light. No matter how high you hang it in the tent with that much light, you should actually notice the best performance with the most clearance as opposed to very close or even at what is considered high normally."


My space is approx 50" x 26". Ive got 4 3590cd [email protected] mounted with 4 vero 29's, v1 @2.1 along a 4 foot x 1 foot bar. (ive also got 1- 48", 54w, t5 uvb)

What's my ppfd and what's a good bet for clearance? I've got plenty of height to move about in.

Thanks folks
 
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Fastslappy

Well-Known Member
I want about 900 or more ppfd in my 8 x 5 room 8 foot ceiling
I wanna have the cobs up high ( I like Tall stuff :) )
& have saturation levels
so far 32 3590 getting their bars soon & be flying high in a week i figure
 

testiclees

Well-Known Member
"What you will need to do to accommodate that much light is to adjust its relative intensity by adjusting the clearance/height. 40cm is too low for that much light"

good info thanks @Greengenes707

Soon after I read that post I raised my light about 6". The plants had an obvious positive response. Madberry had a few leaves that were all akimbo just yesterday. This morning they were re-arrayed like solar panels

EDIT: I come up about 800PPFD when attempting to apply the maths above to my garden set-up.
 

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BOBBY_G

Well-Known Member
ppfd = par watts/sf * 45

so if you have 1000 W @ 60% efficiency thats 600 par watts

say your space is 30SF
thats 600 par W / 30SF = 20 par W/SF
ppfd = 20*45 = 900
 

testiclees

Well-Known Member
ppfd = par watts/sf * 45

so if you have 1000 W @ 60% efficiency thats 600 par watts

say your space is 30SF
thats 600 par W / 30SF = 20 par W/SF
ppfd = 20*45 = 900


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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