• Here is a link to the full explanation: https://rollitup.org/t/welcome-back-did-you-try-turning-it-off-and-on-again.1104810/

200 X Cree XP-G3 on one board

CobKits

CobKits

Well-Known Member
no, you wouldnt use a 1000W at less than 36" from canopy. so basically considering fixture thickness+ canopy height you just burned through 4 feet of he average 8 foot room height really quick. better light coverage is one of teh major reasons cobs outyield hps watt for watt. no stressy hotspots, no larfy darkspots. 25 40W cobs in a 5x5 matrix will embarrass a 1000W HPS every time, apart from efficiency coverage is a major reason. (4) 250W cobs would do the same thing. i dont know how hard you are running those leds but id run 4 of those fixtures at 350 mA ea (just under 1W per chip) and you would just destroy a 1000W HPS
 
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CobKits

CobKits

Well-Known Member
Will-In-China said:
So whats the deal with the 1000W HPS fixtures that kick out over 2000 umol are they actually stunting the plants growth as opposed to helping it?
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more importantly youre confusing overall light output PPF (umol) with PPFD (umol/m^2). a 1000W hps puts out 2000 umol, best used over 2 m^2 to get 1000 umol/m^2
 
Will-In-China

Will-In-China

Member
CobKits said:
more importantly youre confusing overall light output PPF (umol) with PPFD (umol/m^2). a 1000W hps puts out 2000 umol, best used over 2 m^2 to get 1000 umol/m^2
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So my understanding is that PPFD is a measurement taken at one single point, just like you would from a par meter positioned at the top of the canopy, so previously instead of being lazy and typing umol to be perfectly correct should write μmol/m2/s.

Is this how I got things confused?
 
CobKits

CobKits

Well-Known Member
Will-In-China said:
So my understanding is that PPFD is a measurement taken at one single point, just like you would from a par meter positioned at the top of the canopy, so previously instead of being lazy and typing umol to be perfectly correct should write μmol/m2/s.

Is this how I got things confused?
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correct, i was being lazy. ppfd is *always* umol/m^2. we very rarely talk about ppf output of a fixture in umol unless someone is marketing it.
 
Will-In-China

Will-In-China

Member
CobKits said:
no, you wouldnt use a 1000W at less than 36" from canopy. so basically considering fixture thickness+ canopy height you just burned through 4 feet of he average 8 foot room height really quick. better light coverage is one of teh major reasons cobs outyield hps watt for watt. no stressy hotspots, no larfy darkspots. 25 40W cobs in a 5x5 matrix will embarrass a 1000W HPS every time, apart from efficiency coverage is a major reason. (4) 250W cobs would do the same thing. i dont know how hard you are running those leds but id run 4 of those fixtures at 350 mA ea (just under 1W per chip) and you would just destroy a 1000W HPS
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Is the reason for not getting a 1000W HPS that close due mainly to heat? and not so much due to the amount of light, I'm aware there is a light/heat balance. Is this also why we see air cooled hoods trying to remove as much of the hot air as possible? And why we try to keep the canopy below 80F but keep the light as close as we can?

I agree 2000 umol/m2/s in a central spot isnt what I'm aiming for, it is what I have now! I think what I'm working my way up to is covering a 4x4 with as much light as I can, as evenly as possible for 500w from the wall, which is again what I have now. The biggest cost by a long way is the heatsink, and its currently causing the hot spot, it simply has to go.
 
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sixstring2112

sixstring2112

Well-Known Member
CobKits said:
How many hours per day in nature do plants get 115% of full sunlight?
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11 hours in my rooms lol. its not a bad thing to see those high numbers.having to raise the light just means more area covered,or at least it does to me.talk to guys running co2 and tell them less light is more lol
 
MeGaKiLlErMaN

MeGaKiLlErMaN

Well-Known Member
CobKits said:
more importantly youre confusing overall light output PPF (umol) with PPFD (umol/m^2). a 1000W hps puts out 2000 umol, best used over 2 m^2 to get 1000 umol/m^2
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This is why I cant stand hearing people talking about their hotspot being better than anyone elses... like do people not realize that an even canopy is a more efficient usage of space? Idk, what I do know is that the only way to get it is a DIY option or any of the scale-able units from Cutter, Tasty, PLC, or Northern GL.

Also side note that the Citizen CLU058 is the current most efficient COB... Just thought that was cool since Ive thought it was the cxb 3590 for a bit.:clap::clap:
 
CobKits

CobKits

Well-Known Member
Will-In-China said:
Is the reason for not getting a 1000W HPS that close due mainly to heat? and not so much due to the amount of light, I'm aware there is a light/heat balance. Is this also why we see air cooled hoods trying to remove as much of the hot air as possible? And why we try to keep the canopy below 80F but keep the light as close as we can?

I agree 2000 umol/m2/s in a central spot isnt what I'm aiming for, it is what I have now! I think what I'm working my way up to is covering a 4x4 with as much light as I can, as evenly as possible for 500w from the wall, which is again what I have now. The biggest cost by a long way is the heatsink, and its currently causing the hot spot, it simply has to go.
Click to expand...
just get rid of the reflector
 
CobKits

CobKits

Well-Known Member
sixstring2112 said:
11 hours in my rooms lol. its not a bad thing to see those high numbers.having to raise the light just means more area covered,or at least it does to me.talk to guys running co2 and tell them less light is more lol
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what is your setup and have you mapped out your ppfd in your room at the canopy?
 
sixstring2112

sixstring2112

Well-Known Member
CobKits said:
what is your setup and have you mapped out your ppfd in your room at the canopy?
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no mapping.i just run a mix of hps and mh @ roughly 55w per square foot .12kw room .i do own a lux meter and have taken readings from all over the place and i dont have many low light areas.but i run some gavita hung at 9 feet and some cooltubes that almost touch the plants,on movers.lil bit of everything now with the cobs
 
Krippled

Krippled

Well-Known Member
Will-In-China said:
Phpatrick you were right, it was me! For some unknown reason I left of the last number!

2ft = 2000 umol
3ft = 1267 umol
4ft = 885 umol
5ft = 640 umol
6ft = 471 umol
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Will-In-China said:
The cost of CLU058 is more than 50% cheaper on northerngrowlights.com than I can buy it from the local market here. Incredible value!
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Hi Will

Isn't Citizen's cobs all made in Japan??? Is this why it's cheaper in the states. How does that happen??
 
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