Grow Box Ventilation 1000w HPS 4x4x2 space

This is my first grow. I have been using two 4in. inline duct fans that are only rated at 65 cfm free air flow/80 cfm boosted airflow. One is intake and the other is exhaust. I got them at a local hardware store and they are made for boosting the airflow in AC duct pipes in your home. I am on day 16 and I think they are working just fine but I am reading that most people are using much stronger fans. My grow space is 4 ft tall 4 ft deep and 2 ft wide. The 1000w HPS light is outside of the box so I am not having heat problems, but I just want to know if my girls will need more airflow. I also have a 10 in. fan blowing air around on the inside.

Here is pic of the grow box so you can see how the light sits on top so that I can minimize the heat.


And here are some pics my girls at day 16. I think they may be small, but not sure as they are Buddha Red Dwarf and they all seem to be fairly small.


Check out my grow journal I started to see the setup and the progress. Thanks!

https://www.rollitup.org/grow-journals/739860-1st-grow-1000w-hps-indoor.html

might as well shove them into an oven and crank it to 200 degrees ;D

I'd use both the fans for exhaust and just have passive intake.

Thanks ii dP ii. My temp range is consistently between 78 - 82 throughout the day. I have read different things about temp and people seem to disagree most of the time. These are autoflowers and I did read that they do well with high temperatures but I would like to get it cooler since I am pushing it. Do you think using both for exhaust would be more effective than upgrading them both to around 250cfm fans? I had to go cheap since I was out of money at the time, but I could upgrade now.

Hey Boneynerd, I hope it is not that bad! I am a newbie so I am only going off of what I have read. For autoflowers it is said to keep it under 86f. I try to keep it under 80, but sometimes it gets in the lower 80s. But is airflow mostly just to keep the temp down? I am wondering because even if my temps are fine, hypothetically, would I need more airflow for other reasons?

So I found out, not pertaining to temp, but as far as airflow is needed that you just multiply width x height x depth and that is how much cfm is needed. So a 4x4x4 space would only need 64cfm.

I have a removable screen that covers the front door in case I want to leave it open when it reaches 80+ in the box. Is that a bad idea considering my box is in my house and the air is pretty clean? With the door open it stays around 74F.

movement said:

Thanks ii dP ii. My temp range is consistently between 78 - 82 throughout the day. I have read different things about temp and people seem to disagree most of the time. These are autoflowers and I did read that they do well with high temperatures but I would like to get it cooler since I am pushing it. Do you think using both for exhaust would be more effective than upgrading them both to around 250cfm fans? I had to go cheap since I was out of money at the time, but I could upgrade now.

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if you have the ability to upgrade yeah I'd do that. but if you don't I would think just using both fans for exhaust would help a bit, having only active exhaust also creates negative pressure which will with smell. provided you're running a filter on your exhaust or at least pumping it out where nobody can smell the funk. that is if you care about that.