How many led watts per sq ft ?

[Tactical Farmer]

I see Gromau5 said he runs 30w per sq ft and pulls 1.3 - 1.5 GPW.

About what do you guys think the optimal watts per sq ft ?

What numbers are you all running n pulling ?

Currently I have 45 sq ft, 1000w, so I'm at 22.2w per sq ft.

 

[Koondense]

225W in 8sq feet, 1,75g/W
6X Cree cxb 3590 3000 CB 36V(3x@1400mA, 3x@700mA)

 

[Tactical Farmer]

Koon 28.1 watts per sqft

I'm actually at 27 since deducting the one foot side walkway where plants don't grow. Planning on getting over 30 with special spectrums, IR, UV.

 

[growmau5]

I have come to realize that time & space are my biggest limiting factors for production. So I have bumped up a bit since those earlier videos.

example of two different 50 watt cobs ( or 25w per sqft)
cxa3070 @1400ma covering 2 sqft 516 PPFD
cxb3590 @1400ma covering 2 sqft 688 PPFD

so you can do more with less now days.

 

[Koondense]

Koon 28.1 watts per sqft

I'm actually at 27 since deducting the one foot side walkway where plants don't grow. Planning on getting over 30 with special spectrums, IR, UV.

Yep, the plan was to have them full blown at 300W so 37W/ft². After experimenting with dimming one day I forgot to set them on full so I had the two drivers on different currents for most of the flowering time.
The result blew my mind.

I think it's most important to think in terms of PAR W/m²(I prefer metric units because I don't live in ex colony lol.
In my case with CXB3590s and effincencies of around 55% and 63%, this is the percentage of Watts being used for PAR light.
Other leds have different efficencies so the data should be known(put out by manufacturers, but they don't present it) prior to making decisions based on raw electric consumption.

@growmau5
That's a huge difference between cxa3070 and cxb3590! Thanks for your measurement.

Cheers

 

[Dion]

Yep, the plan was to have them full blown at 300W so 37W/ft². After experimenting with dimming one day I forgot to set them on full so I had the two drivers on different currents for most of the flowering time.
The result blew my mind.

I think it's most important to think in terms of PAR W/m²(I prefer metric units because I don't live in ex colony lol.
In my case with CXB3590s and effincencies of around 55% and 63%, this is the percentage of Watts being used for PAR light.
Other leds have different efficencies so the data should be known(put out by manufacturers, but they don't present it) prior to making decisions based on raw electric consumption.

@growmau5
That's a huge difference between cxa3070 and cxb3590! Thanks for your measurement.

Cheers

Don't forget Cambodia, the only other country in the world using inches lol

@growmau5
So nice to have u in this forum dude
What ppfd do u think is best?

 

[AvidLerner]

For vegging 15-25W/SF works great. better nodal growth. For bloom 50W/Sf works great. Design fr 50w/sf and your PPFD should be where you want to be. maybe supplement your HPS with some Cree COB led's low heat and high moles or u/lumens. peace

 

[PetFlora]

It's not about the watts/sft, it's about umoles

Most hi-intensity leds have > the umoles compared to the average cheap led panel

 

[Tactical Farmer]

Krunchbubble starlite cob grow is 50w sqft, looks like I need another 1000w to get into those levels.

 

[noyd666]

was just looking at =nextlight led lights, made in America. look good. like the idea of getting rid of ac etc.

 

[growmau5]

Thanks so much man. There are alot of people doing very cool things with LED over here, I thought I would check it out. lots of cool peeps over here.

I thought/think that 700-800 PPFD is the sweet spot to impress your friends with high GPW figures. for example

A) 850w of cxb3590 @700 ma in a 4x8 tray is 769 PPFD yield 1.9 GPW (~1600 grams dry weight)

B) 1428w of cxb3590 @1050 ma in a 4x10 tray is 985 PPFD yield ( ??? )) I dont know yet, you guys will have to watch my up coming videos.

But the point is, if you can afford the lights, electric, and have the space, why under light the space? Why not shoot for 1000 ppfd in all flowering areas which seems to be the fastest rate of photosynthesis before reaching the point of diminishing returns.

 

[Ichabod Crane]

So if I am shooting for 1000ppfd in 20 square feet am I right in thinking that 16 36v 3500k cxb3590 run at 1.4 ma would get close to that?

 

[Ichabod Crane]

I am thinking of running a scrog similar to this one here with the LEDs.

https://www.icmag.com/ic/showthread.php?t=314837

 

[Phaeton]

Thanks so much man. There are alot of people doing very cool things with LED over here, I thought I would check it out. lots of cool peeps over here.

I thought/think that 700-800 PPFD is the sweet spot to impress your friends with high GPW figures. for example

A) 850w of cxb3590 @700 ma in a 4x8 tray is 769 PPFD yield 1.9 GPW (~1600 grams dry weight)

B) 1428w of cxb3590 @1050 ma in a 4x10 tray is 985 PPFD yield ( ??? )) I dont know yet, you guys will have to watch my up coming videos.

But the point is, if you can afford the lights, electric, and have the space, why under light the space? Why not shoot for 1000 ppfd in all flowering areas which seems to be the fastest rate of photosynthesis before reaching the point of diminishing returns.

The chart fits what I found in my rooms using meters and 15 years of results.
The bud room uses 850 umol of LED and 1050 umol of CMH at the tip of the colas. Multiple overhead lights (CMH at one end blending into LED at the other) and side lights keep the umol count over 500 umol for a sweet spot reaching 30" down the side of the plants.

Watts per square foot was the question. 4400 watts not counting the Far Red in an area 5' x11' is 80 watts per square foot. The umol count varies with spectrum and is controlled by distance.

 

[Tactical Farmer]

Growmau5 current grow - 1428w of cxb3590 @1050 ma in a 4x10 tray is 985 PPFD

40sq ft total room area - 35.7w per sqft at nearly 1000ppfd

 

[Arf]

So how much space can just one CXB3590 3500K 80cri CD bin cover with useful flowering PAR? Everyone tends to do tests with multiple COBs and it make it hard to work backwards to the coverage each device does, because of the overlap from the other COBs, which of course varies by distance between them.

 

[Arf]

Answering my one question a few hours later googling, I found this mob that sells lights based on the CXB3590 3500K CD bin

http://www.tastyled.com/Tasty-T1-2100-LED-Grow-Light-p/t1-2100r.htm

They say a single 3590 3500K COB running at 2.1A trying to cover 24" x 24" gets 480 PPFD which is a bit low, so I guess you would be ok at 18" x 18" or you could drive the COB a bit harder than 2.1A and loose some efficiency.

 

[jikko77]

optic, diffuser ecc ecc modify the cob output.

 

[AvidLerner]

Answering my one question a few hours later googling, I found this mob that sells lights based on the CXB3590 3500K CD bin

http://www.tastyled.com/Tasty-T1-2100-LED-Grow-Light-p/t1-2100r.htm

They say a single 3590 3500K COB running at 2.1A trying to cover 24" x 24" gets 480 PPFD which is a bit low, so I guess you would be ok at 18" x 18" or you could drive the COB a bit harder than 2.1A and loose some efficiency.

CXB's run better at lower amps. I have a185H-240-2100B and I do not use it because I do not need to run CoB's at high rate of watts, when umoles are greater at lower watts, normally between 1050 -1400mA. For vegging I run 700mA - 1050mA, get lost of tight nodal growth on both sativa and Indica. I design twordsd 50w/sf and end up close to 750 PPFD every time, excluding 3w leds. peace
Avid

 

[Arf]

CXB's run better at lower amps. I have a185H-240-2100B and I do not use it because I do not need to run CoB's at high rate of watts, when umoles are greater at lower watts, normally between 1050 -1400mA. For vegging I run 700mA - 1050mA, get lost of tight nodal growth on both sativa and Indica. I design twordsd 50w/sf and end up close to 750 PPFD every time, excluding 3w leds. peace
Avid

I usually go with dimmers, so the exact current is not an issue, just turn the knob. Mainly curious as to the optimal area a single COB can cover, it's always easy to add more COBs, but it's nice to have a clear starting point so you can plan. The watt/sq ft. metric is flawed, as jikko77 pointed out, "optic, diffuser etc modify the cob output" whilst still maintain the same watts to sq. ft. ratio. The naked 3590 COB, with it's 120degree spread, at say 16" above the ground, (which I think gromau5 likes to measure at) would be nice to have a PPFD map of. Unfortunately I only have a ghetto PAR meter, I made by punting a better photo diode into a $10 Chinese eBay Lux meter, and replacing the green filter over it with a magenta underwater GoPro filter, is not calibrated, otherwise I would do the test myself.