4x4 600W tent too hot?

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regd87

Well-Known Member
Hello all,

I'm looking for suggestions to cool my tent down. I have a 4x4 tent set up with a 600W HPS and a 6" inline fan hooked to a carbon filter pulling air out with one flap open. The outside room temp sits around 20-22 degrees. Inside of the tent the temps are hitting close to 28-30 degrees Celcius and my plants are showing what I think may be heat stress.

How can I cool down my tent? It seems that the fan is pulling quite a bit of air out yet it's not cooling it enough - Is it normal for a 600W bulb to raise the temps 6-8 degrees? My only thought is to run an AC unit in the room but I would have to keep the temps close to 16 degrees which is quite cold.

Would another fan pulling air out be a better option? Looking for any and all suggestions.
 
BostonBuds

BostonBuds

Well-Known Member
Do you have a fan in there for circulation? My 400watt hps light can raise the temps 30 degrees F easily without circulation and fan running. You can get an air cooled reflector with another fan also.
 
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regd87

Well-Known Member
Yeah, I have a fan for circulation and it’s still getting really hot. Here is a pic of the setup. Everything I’ve read says that up to 30 degrees is okay but I’m having some issues - it could be light burn?
3035F495-4CB4-49DE-9B7A-B4FEB5092358.jpeg

My plants
D50979F6-EC0A-4F2A-8B20-66972F5DA4BB.jpeg
DA5FFBED-9657-4917-A18B-8D83F0E5CD75.jpeg
 
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Aqua Man

Well-Known Member
Looks like a transpiration issue to me. What's your humidity? I see a little humidifier but if your intaking dry air your humidity will never increase unless the air your drawing in has higher humidity.
 
BostonBuds

BostonBuds

Well-Known Member
I doubt it's light burn, looks like you're plenty far enough away. What type of fan, cfm rating? Try disconnecting the filter from it and see if it lowers the temps in time. Maybe you need a bigger exhaust fan.
 
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Aqua Man

Well-Known Member
nl5xsk1 said:
Running a "open" non air cooled 600 in that setup is definitely problematic, without ac I had to settle with changeup by venting light
Click to expand...
Absolutely agree. 85F is high temp but it can be doable not that i recommend it at all and I hope this doesn't start up the whole VPD argument argument but if you can get your humidity up it should help solve the issue until he can make the needed changes. Again i'm not by any means saying that 85F temps are ideal... atleast not without Co2 (in my opinion) just gonna post this chart that i'm sure most everyone here is aware of and hope i don't start a big debate. I firmly believe in VPD but not pressing it on anyone. This is not exact info as leaf temp would also need to be calculated but would get you in the ball park.

The chart:
 

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regd87

Well-Known Member
TintEastwood said:
Are you exhausting from the tent into the same room? Or outside?

Soil? Coco?
Click to expand...
Running in Fox Farm Ocean Forest. Watering only 6.5 PH'd water and had one feeding of cal mg+ when issues started happening last week.

Aqua Man said:
Looks like a transpiration issue to me. What's your humidity? I see a little humidifier but if your intaking dry air your humidity will never increase unless the air your drawing in has higher humidity.
Click to expand...
Humidity is at 45% in the tent right now, with the temp at 25 - I lowered the bulb ballest to 400W so I'm seeing if the temps still get above 26. It fluctuates usually up to 50%. I can definitely amp up the humidity - I had a large humidifier outside the but it broke so I put the little one in the tent - I wasn't really thinking about the air being pulled in. Definitely good to know.

BostonBuds said:
I doubt it's light burn, looks like you're plenty far enough away. What type of fan, cfm rating? Try disconnecting the filter from it and see if it lowers the temps in time. Maybe you need a bigger exhaust fan.
Click to expand...
The fan has a CFM of 412. I was originally thinking maybe I need a better fan. Is 412 good for 4x4 space?

nl5xsk1 said:
Running a "open" non air cooled 600 in that setup is definitely problematic, without ac I had to settle with changeup by venting light
Click to expand...
Ok, In my other thread someone mentioned dimming the ballest to 400W with my 600W bulb. Currently, the temp is at 25 and climbing - I was hoping it would stay lower with the room temp being about 22. Should I switch to a 400W bulb permanently? Or would an air-cooled hood make a big difference in heat? I was also thinking of switching to LED.

Aqua Man said:
Absolutely agree. 85F is high temp but it can be doable not that i recommend it at all and I hope this doesn't start up the whole VPD argument argument but if you can get your humidity up it should help solve the issue until he can make the needed changes. Again i'm not by any means saying that 85F temps are ideal... atleast not without Co2 (in my opinion) just gonna post this chart that i'm sure most everyone here is aware of and hope i don't start a big debate. I firmly believe in VPD but not pressing it on anyone. This is not exact info as leaf temp would also need to be calculated but would get you in the ball park.

The chart:
Click to expand...
This chart is super useful - to be sure I'm reading it right - I should have an RH of 65-70% even around 24-26 degrees?
 
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Aqua Man

Well-Known Member
regd87 said:
Running in Fox Farm Ocean Forest. Watering only 6.5 PH'd water and had one feeding of cal mg+ when issues started happening last week.



Humidity is at 45% in the tent right now, with the temp at 25 - I lowered the bulb ballest to 400W so I'm seeing if the temps still get above 26. It fluctuates usually up to 50%. I can definitely amp up the humidity - I had a large humidifier outside the but it broke so I put the little one in the tent - I wasn't really thinking about the air being pulled in. Definitely good to know.



The fan has a CFM of 412. I was originally thinking maybe I need a better fan. Is 412 good for 4x4 space?



Ok, In my other thread someone mentioned dimming the ballest to 400W with my 600W bulb. Currently, the temp is at 25 and climbing - I was hoping it would stay lower with the room temp being about 22. Should I switch to a 400W bulb permanently? Or would an air-cooled hood make a big difference in heat? I was also thinking of switching to LED.



This chart is super useful - to be sure I'm reading it right - I should have an RH of 65-70% even around 24-26 degrees?
Click to expand...
Yes that should get you close enough for your setup. I won't get into the whole of it but basically the younger the pant you will want higher humidity on the left and the later you go in flower you will want the lower part of the green on the right if not even yellow. Again I would encourage you to read up on VPD and make up your own mind. There is a lot more to it than the chart linked above. Like how susceptible your strain is told mold etc. can influence where on the chart you want to be. Also there are much better charts that you can use with a VPD calculator that actually takes your leaf temp into account and that's much more accurate than the chart i posted. Take the time to make up your own mind.
 
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Aqua Man

Well-Known Member
I see you also have 2 fans in there... I would recommend you don't have them blowing directly on the plants as this will compound your transpiration issues. Nice gentle breeze in there with indirect airflow
 
IvcusLongDankus

IvcusLongDankus

Well-Known Member
I'm using a 400w hps and 315CMH at the same time but instead of exhausting the air, I pump cold air into the tent. 1Gal humidifier on medium and a oscillating fan on high, I keep it my temps at a steady 78-80F 40RH-50RH.

Cheers, Dankus.

P.S the cold air is provided by a 130$ Window AC from Wal-Mart
 
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regd87

Well-Known Member
Now that I have my air-cooled hood I have my carbon filter and 6"inline fan hooked up to it to create the passive airflow with negative pressure. Should I still run my fan 24/7 to keep the air circulating or have it sync up when the light turns off to also turn off? Will this mess up the bulb if the air is swooshing past it 24/7?
 
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Aqua Man

Well-Known Member
regd87 said:
Now that I have my air-cooled hood I have my carbon filter and 6"inline fan hooked up to it to create the passive airflow with negative pressure. Should I still run my fan 24/7 to keep the air circulating or have it sync up when the light turns off to also turn off? Will this mess up the bulb if the air is swooshing past it 24/7?
Click to expand...
Run it 24/7 for circulation just not directly on the plants as you can cause windburn and transpiration issues. For a tent try to create like a vortex so the fresh air is moving in a circular motion and the exhaust is drawing it upwards.Will help keep temps,humidity etc even and harden the plants a bit. Will not cause any issue with your bulb.

Run all fans 24/7 reason for exhaust is that plants give off Co2 overnight and you don't want it building up, during the day they deplete the Co2 out of the air so it needs to be replenished
 
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regd87

Well-Known Member
Aqua Man said:
Run it 24/7 for circulation just not directly on the plants as you can cause windburn and transpiration issues. For a tent try to create like a vortex so the fresh air is moving in a circular motion and the exhaust is drawing it upwards.Will help keep temps,humidity etc even and harden the plants a bit. Will not cause any issue with your bulb.

Run all fans 24/7 reason for exhaust is that plants give off Co2 overnight and you don't want it building up, during the day they deplete the Co2 out of the air so it needs to be replenished
Click to expand...
Sorry I don’t mean my circulation fan, the inline fan that pulls air through the carbon filter and then exhausts out the air cooled hood.
 
nl5xsk1

nl5xsk1

Well-Known Member
I have small in intake fan attached to port in tent. Its at bottom of tent, this draws cool air from outside of tent ( in basement), which really keeps climate in check. It runs off of a temp control, so when tent gets above 77/78 degrees it draws that cool air in. In addition I installed variable speed controller on exhaust fan, sorta of a poor mans approach but with the size of how it works well. Having a digital ballast is very helpful in early stages I run low to mid range, and crank it up to finish. You are moving in the right direction
 
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