Grow tent ventilation question

[Bluecheeze]

Hello My friends.

So i struggle a bit with heat in My grow tent, it gets 32-33c when lights on.

But i got a Nice negative pressure i can see the tent sucks in, and inside i have a clip fan to circulate the air at plant level.

When i feel with My hand in the tent it really does not feel like 32c, more like 26-28c and there is a soft wind at the bottom of tent.


So My questions:

1. Can My thermometer be incorrect? It is new i opened it 4 days ago. I have tried to put it in the shadow under a pot and the Wiré at ny plants, still shows High temps...

2. If you look down at left My passive intake is there, My carbon filter is just above it.
Should i change position to right in tentans do i get Lower temps that way? But then that way the filter gonna be right at the door.

Please help Me this is 3rd night for My seedlings with this temps.

They dont look sad tho, green and healthy and is about 2 inches now on the 4th day above ground.


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[odinsmaster]

I run two thermometers in my tent, one on the ground and one half way up the wall. The one on the ground gets in the 90f plus range but the one on the wall never gets over 85f. At first I was worried about it. But my plants do not seen to stress out over the heat.

Odinsmaster's Soil Girl Scout Cookies Grow Journal - 2016

 

[Major PITA]

Thermometers are cheap. Get another to verify the readings you are seeing from the one you have.
Dark green leaves directly under the light will be warmer than a hand placed briefly into the tent.

 

[Bluecheeze]

Thermometers are cheap. Get another to verify the readings you are seeing from the one you have.
Dark green leaves directly under the light will be warmer than a hand placed briefly into the tent.

Okey but how do i know if My plant does not like it? Will i notice somthing or do they just die? They look good now even tho the High temps. So maybe wrong readings then?


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[Major PITA]

Okey but how do i know if My plant does not like it? Will i notice somthing or do they just die? They look good now even tho the High temps. So maybe wrong readings then?

If they died, you'd know it long beforehand something was wrong. You can search for heat stressed plants to see pictures. The leaves will usually curl up (taco) to limit their exposure to the heat source. This is different than light burn because of being too close to a light source. That will burn leaves, making them bleached or brown and dry.

 

[Bluecheeze]

If they died, you'd know it long beforehand something was wrong. You can search for heat stressed plants to see pictures. The leaves will usually curl up (taco) to limit their exposure to the heat source. This is different than light burn because of being too close to a light source. That will burn leaves, making them bleached or brown and dry.

Okey thank you!

If i change My carbon filter to the right side of the tent right at the door so it isnt right above the passive intake, will that make any difference with temps?

Or does it matter as i have and fan in the tent that circulates at in there.

Or do i just need a exhaust? Now i got an 164 cfm exhaust, will an upgrade to a 210 cfm make a difference ?


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[Major PITA]

Okey thank you!

If i change My carbon filter to the right side of the tent right at the door so it isnt right above the passive intake, will that make any difference with temps?

Or does it matter as i have and fan in the tent that circulates at in there.

Or do i just need a exhaust? Now i got an 164 cfm exhaust, will an upgrade to a 210 cfm make a difference ?

I wouldn't move the filter. I doubt it would help.
How big is the tent? How honest is that 164 cfm rating? Some small inline duct fans are rated much higher than they actually do, especially when running through filters.
Do you need to start under that light? I use a small T5 fixture to give them a little more gentle start. It, or CFLs would solve your heat problem while plants are small and getting established.

 

[Bluecheeze]

I wouldn't move the filter. I doubt it would help.
How big is the tent? How honest is that 164 cfm rating? Some small inline duct fans are rated much higher than they actually do, especially when running through filters.
Do you need to start under that light? I use a small T5 fixture to give them a little more gentle start. It, or CFLs would solve your heat problem while plants are small and getting established.

The tent is 90x90x170 cm, the exhaust fan is a cheap very plastic one, i will buy the one that is 211 cfm and it look like more quality and it should be more silence too.

I dont got any other light right now and My last money i spend on the new exhaust fan and a new clip fan.

Do you think it will help My High temps? I will open more passive intake when i have changed the exhaust fan.


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[Major PITA]

The tent is 90x90x170 cm, the exhaust fan is a cheap very plastic one, i will buy the one that is 211 cfm and it look like more quality and it should be more silence too.

I dont got any other light right now and My last money i spend on the new exhaust fan and a new clip fan.

Do you think it will help My High temps? I will open more passive intake when i have changed the exhaust fan.

I think a lot of the difference a bigger fan makes depends on the temperature of the air going into the tent. It is difficult to reduce 32C in the tent by sucking in 26C air. Are you able to get cool (outdoor?) air into the tent? I run a 440 CFM fan in a space that is roughly 100 x 120 x 240 cm. It works great for me, but I do not grow during the summer. No matter how much air I pull though, it gets too warm.

 

[Bluecheeze]

I think a lot of the difference a bigger fan makes depends on the temperature of the air going into the tent. It is difficult to reduce 32C in the tent by sucking in 26C air. Are you able to get cool (outdoor?) air into the tent? I run a 440 CFM fan in a space that is roughly 100 x 120 x 240 cm. It works great for me, but I do not grow during the summer. No matter how much air I pull though, it gets too warm.

Well My grow tent is in a closet :

So i can not get air from outside but i exhaust from the tent and i made a hole in the wall and blow the air out in another room:

But i got this ventilation thing that is in the floor that blow out Fresh cool air and it is next to My passive intake:

and i got 10 little smaller maybe 10mm Holes in the Wall from My bedroom in to the closet plus there is this gap down at the door, maybe 1 inch so i think i get air in and out from there but i dont know i never Done this before it is My first time



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[Bluecheeze]

Now the leaves are curling up.. I get My new exhaust tomorrow will they make it one more night?


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[Major PITA]

Now the leaves are curling up.. I get My new exhaust tomorrow will they make it one more night?


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Dunno. You are the best judge since you are there and have the complete picture.

 

[Bluecheeze]

Dunno. You are the best judge since you are there and have the complete picture.

Yeah ofcourse only i can know withot posting pics but i ment is the process for the plant to die fast or does it take a couple of days because i never Done this before i will install the new exhaust and clip fan as soon as they arrive, if that dont help i dont think there is anything to do.

But thanks for your help My friend!


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[Major PITA]

I doubt another day will make it or break it.
I'm still skeptical a new fan will make much difference. If you were pulling 18C air into the tent, it would help. But moving more warm air around doesn't cool a tent all that much. and

 

[Bluecheeze]

I doubt another day will make it or break it.
I'm still skeptical a new fan will make much difference. If you were pulling 18C air into the tent, it would help. But moving more warm air around doesn't cool a tent all that much. and

Okay so My new exhaust came today but when i bought it it Said on website 211 cfm so i figured it would work fine with My 176 cfm carbon filter as i have read i remove 20% for the carbon filter. But now on the label on the exhaust fan i can choose 2 modes - 129cfm or 235cfm ( on website it Said Max 211cfm ), AND on the Box it says " highest airflow up to 247cfm" . Is this filter to small? I got 3 90degrees turns on the ventilation duct If that does matter.

The exhaust fan moves alot more air and thats good i think, i opened more passive so now My passive is about 3 times bigger than the exhaust, atleast twice as much air comes out from the exhaust now and it feels cooler too, lets see when lights on in about 2,5 hours.


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[Major PITA]

For cooling, go with the highest CFM. For less odor, go with the lowest CFM.
With a filter and three 90 degree elbows, the fan won't come close to its rated output.

 

[Bluecheeze]

For cooling, go with the highest CFM. For less odor, go with the lowest CFM.
With a filter and three 90 degree elbows, the fan won't come close to its rated output.

Well at this time the other days My temps have Been 32-33c, now My temps are 26.2 and i dont think it will Go above 26,5c but lets see


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[Bluecheeze]

Now i am just worried about the carbon filter, i think i maybe will buy a 235cfm Presh carbon filter when i get My money in about 20 days. It's 100 $ extra tho and the new exhaust costed Me another 100$..


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