Temperature problem with CXB Cobs

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OGHulk

Member
i'm having problem controlling the temp inside my growbox
i have 16 cxb3590, and when all power them all the temp goes up to 95 °F, when i power 8 of them (200w) the temp below the cobs goes up to 83 in a matter of minutes even when the heatsinks are still cold and the tent still open, i can feel the heat below the cobs

needles to say it's impossible to use all the 16 with the tent closed
Also the heatsinks radiate the heat inside the growbox and i don't know how to evacuate it, the exhaust fan can only lower temp by a few degrees
i have a 4x2x5,90 grow tent
 
Mullumbimby

Mullumbimby

Well-Known Member
It would really help to know what amps you are running your lights at - if you tell us the exact specs of your drivers, there will certainly be someone in here shortly to give this answer, if you don't know it already.
You've got about 1 sq metre there, which needs between 35,000 and 50,000 Lux. If you give it 50,000, you're running a very seriously bright tent.
Just guessing here (ie I'm too sketchy to do the real work), but you'd have about the right amount of light in that tent if your 16 CXBs are running below .7 amps, which is not much at all, compared to their maximum capacity.
 
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O

OGHulk

Member
Mullumbimby said:
It would really help to know what amps you are running your lights at - if you tell us the exact specs of your drivers, there will certainly be someone in here shortly to give this answer, if you don't know it already.
You've got about 1 sq metre there, which needs between 35,000 and 50,000 Lux. If you give it 50,000, you're running a very seriously bright tent.
Just guessing here (ie I'm too sketchy to do the real work), but you'd have about the right amount of light in that tent if your 16 CXBs are running below 7 amps, which is not much at all, compared to their maximum capacity.
Click to expand...
i'm running the leds at 25w each, i use two 200 watts drivers
 
Kul

Kul

Active Member
I've run 400w cob in a 4x2 with 8 cobs and it was a pain to keep cool. I would suggest a 4x4, you'd have a wonderful spread with 16 cobs.

Post pics of your tent setup sounds like your not pulling the hot air out fast enough.

What's your ambient room temp?

Also remote mounting drivers will help keep the tent cool.
 
Mullumbimby

Mullumbimby

Well-Known Member
Based on data for a 3,000K CXB3590 found here: https://www.rollitup.org/t/cob-efficiency-spreadsheets.865238/
and using the data you have provided, you should be producing about 76,208 Lumens, which in your approximately 0.9 square metres, equals 68,000Lux (Lumens per square metre).
I'm often wrong but, if I'm right, this is more than half the maximum power of direct, uninterrupted sunlight: https://en.wikipedia.org/wiki/Lux
The recommendation that I have heard for maximum growth is between 35,000 and 50,000 Lux.
12 of those COBs at 25W each should be enough in your space (shitloads actually lol).
 
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OGHulk

Member
Kul said:
I've run 400w cob in a 4x2 with 8 cobs and it was a pain to keep cool. I would suggest a 4x4, you'd have a wonderful spread with 16 cobs.

Post pics of your tent setup sounds like your not pulling the hot air out fast enough.

What's your ambient room temp?

Also remote mounting drivers will help keep the tent cool.
Click to expand...
my drivers are outside the tent
the room temp is around 75°F
even with the exhaust fan set to max the tent can only go down to 84 degree but i can't run it to max because of the noise
maybe the problem is the fan which seem too small to move the air effectively


 
O

OGHulk

Member
Mullumbimby said:
Based on data for a 3,000K CXB3590 found here: https://www.rollitup.org/t/cob-efficiency-spreadsheets.865238/
and using the data you have provided, you should be producing about 76,208 Lumens, which in your approximately 0.9 square metres, equals 68,000Lux (Lumens per square metre).
I'm often wrong but, if I'm right, this is more than half the maximum power of direct, uninterrupted sunlight: https://en.wikipedia.org/wiki/Lux
The recommendation that I have heard for maximum growth is between 35,000 and 50,000 Lux.
12 of those COBs at 25W each should be enough in your space (shitloads actually lol).
Click to expand...
the problem is that even if i run 8 of them (like in the picture) the temperature is still a problem, right now the temp is 84
 
BM9AGS

BM9AGS

Well-Known Member
Mullumbimby said:
Based on data for a 3,000K CXB3590 found here: https://www.rollitup.org/t/cob-efficiency-spreadsheets.865238/
and using the data you have provided, you should be producing about 76,208 Lumens, which in your approximately 0.9 square metres, equals 68,000Lux (Lumens per square metre).
I'm often wrong but, if I'm right, this is more than half the maximum power of direct, uninterrupted sunlight: https://en.wikipedia.org/wiki/Lux
The recommendation that I have heard for maximum growth is between 35,000 and 50,000 Lux.
12 of those COBs at 25W each should be enough in your space (shitloads actually lol).
Click to expand...
We here prefer to go off PPFD. lumens are in the color range we don't so much care about. He's pulling about 1300 PPFD and the max a plant can take is 1500 PPFD with 1500ppm of co2 and 86deg F.

Also @OGHulk talk to realstyles, timber grow lights or Robincnn. They can probably give you a good deal on a B series driver with the pot if you don't have it already. With 1300ppfd you're likely gonna wanna dim them a bit. Especially when in veg.
 
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OGHulk

Member
bizfactory said:
Is that just a duct booster fan? If so, thats your problem, they can't move much air on their own. You can also consider dimming you driver. Do you have the A or B version? assuming it's a meanwell.
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it's an inline duct fan ( RVK sileo 125E2-L) it can move up to 323 m3/hour but i decreased the speedto minimum because of the noise

i don't want to dim the drivers, i want to grow under 400w
 
BM9AGS

BM9AGS

Well-Known Member
bizfactory said:
Where's that info from and what does it say with no CO2 boost?
Click to expand...
I'd have to find the study. It's somewhere on the web. So basically with out co2 then all the other levels need to go down. Heat and light. Those levels were established to be the most effective levels a plant could take but if you take 1 away then the high heat or co2 could do more bad than good if I remember. I'm sure you or someone could find the study. I'll look for a bit.

@OGHulk fyi. A lot of growers are using 750ppfd for optimum yields and having problems above that. So you need to dim
 
O

OGHulk

Member
BM9AGS said:
We here prefer to go off PPFD. lumens are in the color range we don't so much care about. He's pulling about 1300 PPFD and the max a plant can take is 1500 PPFD with 1500ppm of co2 and 86deg F.

Also @OGHulk talk to realstyles, timber grow lights or Robincnn. They can probably give you a good deal on a B series driver with the pot if you don't have it already. With 1300ppfd you're likely gonna wanna dim them a bit. Especially when in veg.
Click to expand...
i have the B version of the MW
is 1300ppfd alot even for 3 plants ?
 
Resinhound

Resinhound

Well-Known Member
OGHulk said:
it's an inline duct fan ( RVK sileo 125E2-L) it can move up to 323 m3/hour but i decreased the speedto minimum because of the noise

i don't want to dim the drivers, i want to grow under 400w
Click to expand...
Even if you get Temps under control, I predict you are going to cook those plants under that kind of light. Just too damn much. Yes you can have too much of a good thing.
 
BM9AGS

BM9AGS

Well-Known Member
OGHulk said:
i have the B version of the MW
is 1300ppfd alot even for 3 plants ?
Click to expand...
Sweet. Just get a potentiometer they're pocket change. You could drop to half power and be right around ideal unless you get some co2

If you manifold those plants I bet it wouldn't be hard to get 2gpw at half power on drivers.....you need a bigger tent 12-15sqft
 
BM9AGS

BM9AGS

Well-Known Member
Ohh spray paint the tops of those buckets white. Sides too if you can manage. Or I've seen a guy buy cheap car sunshades at the dollar store and cut them to go over the buckets. That'll be too hot for your growing method unless you're running a chiller
 
O

OGHulk

Member
BM9AGS said:
Sweet. Just get a potentiometer they're pocket change. You could drop to half power and be right around ideal unless you get some co2

If you manifold those plants I bet it wouldn't be hard to get 2gpw at half power on drivers.....you need a bigger tent 12-15sqft
Click to expand...
2gpw would be crazy, i would be happy to pull half that lol
i could decrease the power as i already soldered the potentiometers or i could just power off a driver which one would be the best option ?
 
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