3x3x6.5 tent 400w HID Temps too high

I have a 3x3x6.5 tent with a 400w light passive intake ducting connecting from both ends of reflector exiting the tent with a hole opened up at bottom for fresh hottest temp its reach has been 27-28°c while on Res temp is 3 degrees cooler. Humidity hangs around 41-47%.
I'm not sure if this is considered a sealed grow space since I have an opening at the bottom but I'm using Co2 pads as well as two desktop fans one blowing across my Res the other pointed at my grow light. I just bought a cool mist humidifier hopefully this helps. Another factor I know is allowing temps to get high is the fact I have no extra ducting venting out the hot air but that will Soon be rectified. I want to avoid buying another a/c as I already have a portable one running in my front room (only strong enough to cool living room) don't need more bills

I had a similar issue and temps with my plants in bloom, I added a 6" inline exhaust and it helped and so that should help you also. I think once you have that exhaust it may be considered negative pressure look that up and you can determine for sure.

GrnMonStr said:

I had a similar issue and temps with my plants in bloom, I added a 6" inline exhaust and it helped and so that should help you also. I think once you have that exhaust it may be considered negative pressure look that up and you can determine for sure.

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I already have a 6"inline fan exhausting the air out of the HID itself which causes no negative pressure. All I have to do is disconnect the ducting from the reflector opposite from exhaust fan and it creates negative pressure but it doesn't make much difference in the temp I just figured the negative pressure was sucking up the Co2 so I reattached the ducting.

I think you will need to forget about the loss of co2 and add a second exhaust fan to suck in cooler room air from a bottom opening. Once a plant is taking up space your temps will be too high otherwise.

So you thin

GrnMonStr said:

I think you will need to forget about the loss of co2 and add a second exhaust fan to suck in cooler room air from a bottom opening. Once a plant is taking up space your temps will be too high otherwise.

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So you think negative pressure would be better? I just figured I'd the plant really got to utilize the Co2 the plant would be able to withstand higher temps. Shit I may just have to cash out on an a/c

Try adding some ducting to take the hot exhausted air further away from the tent.
Ridged ducting allows for better airflow.
negative pressure is common, my tent walls are bowed in.
6" maxxfan exhaust 420cfm on level 3, currently on level 2@320?cfm, with a 4" ducting booster fan as my intake fan; aswell as haveing one of the screened ports open for natural draft.
My temps are similar, currently 27.5

I think you would be better off disconnecting the duct and placing the open end under your light. For two reasons. You would be pulling heat being emitted downwards from under the hps bulb. And you would be created negative pressure. Once ur negative pressure is there, open a couple holes in the tent and the pressure will help pull in fresh air from outside the tent. I was having heat issues as well untill I tried this. I was even able to add an 450watt led to my 400 hps setup without having temps going up. And I'm only running a 4 inch inline fan. Here's a pic of my set up