Excessive Heat Issue In Grow Tent

GKM420

Active Member
Hi Everyone,

I have the same problem that many others have-excessive heat in grow tent-and can't seem to find a good solution from other threads. I was hoping someone might have had the same experience as myself, and found a reasonable solution.

I have a 4' x 3' grow tent with 2 x Kingbrite 240W LED lights and an AC Infinity S6 (6 inch) inline fan. The humidity is very low (25-30%) so I've ordered a small humidifier. That should help the humidity levels a bit and I'm hoping maybe it will help lower the ambient grow tent temperature, as well, but we'll see. The grow tent air is exhausted out of the room the tent is in. The temperature of the room is a constant 22 degrees Celsius/72 degrees Fahrenheit. I'm running 4 autos, the oldest being one month old.

When I have both lights running at 150 W each (300 W total) the temperature in my grow tent rises to around 29 degrees Celsius/84 degrees Fahrenheit. If I understand correctly, temperatures should be no higher than 27 degrees Celsius/80 degrees Fahrenheit.

Lowering the wattage output of the lights to 100 W each (200 W total) takes the temperatures down to around 26 degrees Celsius/79 degrees Fahrenheit. This is an acceptable range but now my problem is I have the ability to use up to 480 W of light total, but am using less than half the available output. I've seen people who have grown nice plants with just 200 W, but it sucks having the ability to use much more power but not being able to.

I'm a new grower, and am thinking I probably should have done more research before buying these lights...$600 CAD for these two lights, when I could have probably bought two Mars Hydro TS600 for one-third of the price is kind of depressing. I guess I can chalk it up to an expensive learning experience!

Another problem I'm facing is my grow tent is in the same room my wife and I use as a home office, meaning I can't crank up the fan to much higher than 3/8 in terms of settings. Again, probably another thing to chalk up to a learning experience! I'm guessing if I was able to crank the fan up to 5/8 or 6/8 it would help a lot but the noise level is far too high for my wife.

Aside from trying to use a portable air conditioner, is there anything else I can do? Running the lights at night won't change anything; the room is at a constant 22 degrees Celsius/72 degrees Fahrenheit. I can't move the tent out of the room, regrettably. Maybe I just don't have a great setup to start with and am stuck leaving the lights really low?

Thank you kindly in advance!
 

.Smoke

Well-Known Member
Yeah, unfortunately in your setup, getting lights with an external driver/ballast that you can place outside the tent is about your only option.
(Q-boards with external drivers are probably the easiest/cheapest route, but I don't use led so I could be wrong)
 

GBAUTO

Well-Known Member
I normally run my room at 83-84 degF.
My leaf surface temps are typically around 79 degF and they are quite happy.
I think the biggest challenge facing you would be to able to maintain a higher RH% in your lung room.
Can you either link the fixtures you bought or a pic.
Most of the fixtures I've seen from them allow you to remote mount the driver.
I made a mounting panel for my drivers, switches, and ventilation control so they are all outside of the room.
That will remove a small amount of heat from the tent.
Can run your lights when you won't be using the office?
My main grow is a walk-in closet in an upstairs bedroom.
The lung room temps are typically 10-14 degF cooler than my target grow temp.
I have run my lights at night because the lung room will heat during the day enough so I don't have that 10 deg. difference.
It's about 300 ft3 and I use the T6 fan for ventilation.
I run almost a kw of leds in there.
If the lung room warms up so that there isn't that 10 degF difference, the grow temps will climb.
What type of medium are you growing in?
 
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curious618

Well-Known Member
Yeah, unfortunately in your setup, getting lights with an external driver/ballast that you can place outside the tent is about your only option.
(Q-boards with external drivers are probably the easiest/cheapest route, but I don't use led so I could be wrong)
I run a Chinese knockoff 240W QB that I got for less than $200 on Amazon. Temps don’t increase too bad at all and you have the ability to mount the driver outside the tent if you want. Only my second grow bite it’s been solid. Could get two of those and be solid. Just my two cents.
 

GKM420

Active Member
Yeah, unfortunately in your setup, getting lights with an external driver/ballast that you can place outside the tent is about your only option.
(Q-boards with external drivers are probably the easiest/cheapest route, but I don't use led so I could be wrong)
Thanks for the reply! The two Meanwell drivers for the lights are already mounted outside the tent though...I can't imagine how much worse the heat issue would be with them inside the tent! The drivers are almost too hot to touch when powered up to around 150W.
 

GKM420

Active Member
I normally run my room at 83-84 degF.
My leaf surface temps are typically around 79 degF and they are quite happy.
I think the biggest challenge facing you would be to able to maintain a higher RH% in your lung room.
Can you either link the fixtures you bought or a pic.
Most of the fixtures I've seen from them allow you to remote mount the driver.
I made a mounting panel for my drivers, switches, and ventilation control so they are all outside of the room.
That will remove a small amount of heat from the tent.
Can run your lights when you won't be using the office?
My main grow is a walk-in closet in an upstairs bedroom.
The lung room temps are typically 10-14 degF cooler than my target grow temp.
I have run my lights at night because the lung room will heat during the day enough so I don't have that 10 deg. difference.
It's about 300 ft3 and I use the T6 fan for ventilation.
I run almost a kw of leds in there.
If the lung room warms up so that there isn't that 10 degF difference, the grow temps will climb.
What type of medium are you growing in?
That's really encouraging to know that the temps might be okay, assuming I can raise the humidity! Thanks for replying. The drivers are already mounted outside the tent and my light cycle is 18/6 because they're all autoflowers...The ambient temperature of the room doesn't vary so I don't know if running them at night would help. The room the tent is in is at a constant 22 degrees Celsius/72 degrees Fahrenheit at night and during the day.

I have a humidifier on the way and hope it arrives soon. My humidity levels are around 25-30% so definitely an issue that needs addressing. Maybe that will be enough to keep my ladies healthy.

I'm using soil as the medium. Would like to try coco someday, but since I'm a beginner, I thought soil might be best to start with.

I think I'll just have to try bumping up the humidity and hoping all is well. I understand that mold can be a big problem with high temperatures and high humidity, so I'll need to be careful.

Here's a link to the lights I have (KingBrite 240w v3 QB light with Samsung LM301H and Epistar 660nm red)


I'll make sure to update everyone when my grow finishes, assuming I make it that far :)
 

bernie344

Well-Known Member
Hi Everyone,

I have the same problem that many others have-excessive heat in grow tent-and can't seem to find a good solution from other threads. I was hoping someone might have had the same experience as myself, and found a reasonable solution.

I have a 4' x 3' grow tent with 2 x Kingbrite 240W LED lights and an AC Infinity S6 (6 inch) inline fan. The humidity is very low (25-30%) so I've ordered a small humidifier. That should help the humidity levels a bit and I'm hoping maybe it will help lower the ambient grow tent temperature, as well, but we'll see. The grow tent air is exhausted out of the room the tent is in. The temperature of the room is a constant 22 degrees Celsius/72 degrees Fahrenheit. I'm running 4 autos, the oldest being one month old.

When I have both lights running at 150 W each (300 W total) the temperature in my grow tent rises to around 29 degrees Celsius/84 degrees Fahrenheit. If I understand correctly, temperatures should be no higher than 27 degrees Celsius/80 degrees Fahrenheit.

Lowering the wattage output of the lights to 100 W each (200 W total) takes the temperatures down to around 26 degrees Celsius/79 degrees Fahrenheit. This is an acceptable range but now my problem is I have the ability to use up to 480 W of light total, but am using less than half the available output. I've seen people who have grown nice plants with just 200 W, but it sucks having the ability to use much more power but not being able to.

I'm a new grower, and am thinking I probably should have done more research before buying these lights...$600 CAD for these two lights, when I could have probably bought two Mars Hydro TS600 for one-third of the price is kind of depressing. I guess I can chalk it up to an expensive learning experience!

Another problem I'm facing is my grow tent is in the same room my wife and I use as a home office, meaning I can't crank up the fan to much higher than 3/8 in terms of settings. Again, probably another thing to chalk up to a learning experience! I'm guessing if I was able to crank the fan up to 5/8 or 6/8 it would help a lot but the noise level is far too high for my wife.

Aside from trying to use a portable air conditioner, is there anything else I can do? Running the lights at night won't change anything; the room is at a constant 22 degrees Celsius/72 degrees Fahrenheit. I can't move the tent out of the room, regrettably. Maybe I just don't have a great setup to start with and am stuck leaving the lights really low?

Thank you kindly in advance!
Plants still perform good @ 30C.
 

GKM420

Active Member
I run a Chinese knockoff 240W QB that I got for less than $200 on Amazon. Temps don’t increase too bad at all and you have the ability to mount the driver outside the tent if you want. Only my second grow bite it’s been solid. Could get two of those and be solid. Just my two cents.
Thanks for the reply! These are Chinese lights too, from Alibaba. Unfortunately, they weren't all that cheap when the exchange rate from USD-CAD was factored in. The drivers are already mounted outside the tent, but thanks for mentioning!
 

GKM420

Active Member
Plants still perform good @ 30C.
Man, that's really good to hear! I'm going to try and raise the humidity to an acceptable level and hope that helps the plants. Will let you all know in a few months when they're (hopefully) ready for harvest!
 

GKM420

Active Member
So just to follow up, I'm going to take the advice posted here and just keep my lights on 150 W each (300 W total) but also raise the humidity. I'll have to take a look but I'm guessing around 40-50% is probably good from what I see. I'm a little worried about mold but I have an oscillating fan in addition to my AC Infinity S6, so hopefully that will help with the mold.

Thanks everyone, and I'll update in a few months when I've hopefully had my first-ever harvest! I'm running four autoflowers:

Canuk Cookies (Canuk Seeds)
Northern Lights #5 (Seedbank.co)
Peachy CBD (White Widow Seedbank)
Lemon Pie (White Widow Seedbank)
 

GKM420

Active Member
Get a bigger fan and duct and run it on a lower setting. That should give you more air flow with the same amount of noise
I've already spent so much money on this equipment, I think my wife would kill me if I bought more! Good suggestion though. I started off with a 4 inch fan and quickly realized that was too small. Luckily, I was able to return the 4 inch and get a 6 inch instead. I can't return the 6 inch fan, so I'm stuck with it.

For anyone reading this and wondering about fan sizes, go bigger! It's better to get a bigger one in the beginning, rather than upgrade later on.
 

Imcamping86

Well-Known Member
Usually with led , you want your temps in the mid 80s . I run mine at 83-84 f when they are this high are your plants showing signs of stress ?
 

jondamon

Well-Known Member
Another thought is that you haven’t mentioned where your exhausted air is going to?

Is this dumping into the home office?
 

GKM420

Active Member
Another thought is that you haven’t mentioned where your exhausted air is going to?

Is this dumping into the home office?
No, it's being piped out into the hallway outside the home office. I've been checking the temperature of the office, and it's fairly consistent. Hovers around 21.5-23 degrees Celsius (71-73.5 degrees Farehneit). So, when my lights are on 100 W each (200 W total) the temperature fluctuates but is consistently around 25-27 degrees Celsius (77-81 degrees Farenheit) inside the tent.

Raising the output of the lights even a bit (230-250 W total), jacks the temperatures up to around 27-28 C/80-82 F, inside the tent. Maybe with my new humidifier those temps would be okay?
 
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GKM420

Active Member
Here's an update with photos!

I'm having trouble figuring out if the oldest plant (Canuk Cookies) in the back, is suffering from heat stress, over/under watering, nutrient deficiency/nutrient toxicity, etc.

The Canuk Cookies plant perked up after a small watering yesterday. I lost my first grow due to mold (over watering + temps too high, is my guess) so I'm trying to figure out how to water plants properly. I'm now waiting until the top soil is totally dry up to my second knuckle before watering. Because of the heat, maybe I'm waiting too long though.

All plants, with the exception of the Canuk Cookies, appear to be suffering from stunted growth. The leaves appear okay but the growth is very slow. I'm guessing that's probably due to a lack of light. I'm worried about lowering the light again though due to previously mentioned heat issues. These lights run hot! Too hot. Maybe also genetics? The Northern Lights #5 (in front of the Canuk Cookies) was very slow to start but is getting bigger more quickly now. The two seedlings (Peachy CBD and Lemon Pie CBD) are super-slow. Again, I'm guessing it's lack of light but could be heat stress and /or genetics also?

The Canuk Cookies looks okay on top, with the exception of some clawing. The lower leaves, however, are yellowing and dying. It's lost about 3-4 leaves in the last week. I'm thinking under watering +heat stress. What do you guys think?

I finally got a humidifier, which I'll install today. I'm hoping that will help a lot.

Thanks, as always, for any and all advice!

Edit: My camera filter makes these pictures look more yellow than they are in person. The Canuk Cookies does have yellowing on the bottom leaves as mentioned, but the other plants are a healthy green colour.
 

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GKM420

Active Member
Usually with led , you want your temps in the mid 80s . I run mine at 83-84 f when they are this high are your plants showing signs of stress ?
You don't have any issues with heat stress at those temperatures? What are your humidity levels like in veg/flower?
 

Imcamping86

Well-Known Member
You don't have any issues with heat stress at those temperatures? What are your humidity levels like in veg/flower?
I’m current veg . 1 month and change . Temps and rh 18 hours at 84 f and 59rh , I set my controllers to allow fluctuations of 2 . And at night for 6hrs they get 73 f and 50 % humidity. It’s been this way their whole life besides seedlings . No problems other than some light stress .
 

GKM420

Active Member
I’m current veg . 1 month and change . Temps and rh 18 hours at 84 f and 59rh , I set my controllers to allow fluctuations of 2 . And at night for 6hrs they get 73 f and 50 % humidity. It’s been this way their whole life besides seedlings . No problems other than some light stress .
Thanks! I'm going to try and get my RH up ASAP! After that, I'll start to slowly raise the output on the lights and see what happens.
 
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