Air circulation

I’m going to make a small grow box to take one plant. Approximately 1m x.5 x.5. A duct fam seems a bit excessive. What can u use and what rule of thumb do I need to circulate the air? I’ve seen total area needs to be vented in 5mins?

Well venting for heat you want to exchange the volume of the space 2 - 2.5x a minute. Calculate your volume in cubic feet and multiply it by 2 or 2.5 and aim for that many CFM.

You can measure it in inches, multiply the LxWxH and divide that by 1728 to get cubic feet.

Just as Renfro said...I know that it seems kind of overkill, but oftenly people don't realize that airflow is one of the primary factors in a grow.

I'd get a 4-6 inch inline fan in the 300-400 cfm range that can be turned down.

Ya, you will definitely want to get some decent air circulation going, especially in a small tent because you want to replenish the c02 as well. You don't want your plants growing in stale air. Without proper circulation it can also get hot in your tent.

Good luck man

Make sure you don't have poor circulation in the lower left side.

Rule of thumb is 8 times volume per hour

Maine207Medical said:

I'd get a 4-6 inch inline fan in the 300-400 cfm range that can be turned down.

Click to expand...

What is cfm range

Antler2510 said:

What is cfm range

Click to expand...

It stands for cubic feet per minute. A inline fan with 300-400 cfm would exchange the air and keep it cool in the space you're growing in.

DaFreak said:

Rule of thumb is 8 times volume per hour

Click to expand...

I thought it was 2 - 2.5 x per minute.

Know that some blowers (the good ones) are loud at full speed. One could use a larger sized blower with a speed control to slow it down and minimize the noise. I have a 2x4 tent with a 10 inch vortex that is way overkill at 791 CFM but I run it on a variac at 35 volts instead of 120 and it moves plenty of air and you can't hear it at all. I can run it slower or faster if needed. If I do something bigger in the future and need all that CFM then it's available.

The centrifugal blowers are the ones that will move the most air and they cope much better with static pressure loses (restrictions) like duct work, bends, light hoods, carbon filters... At full speed they can be loud. Good ones are pricey but they last a long time. Cheaper ones will work for a year or two and the bearings will give out, they are also a little louder generally. My favorite brand is vortex, VTX series.

Renfro said:

I thought it was 2 - 2.5 x per minute.

Click to expand...

Lol, well it’s my memory from the OverGrow days so I could be off. Google gave me this
“Ideally, your grow room air should be renewed at least once every 5 minutes.*
From some site called hydrotex. That would make it 8 times in 40 minutes. I pretty sure other factors like heat, odor control are really the deciding factors and anybody with even the cheapest fan has adequate exchange as far as replenishing the co2 etc.

Yeah the CFM required to move the heat is the key. Most people are cooling some HPS lights with air thats around 70 degrees, so I say 2 - 2.5x a minute as a general rule. If someone is pulling in air thats 28 degrees the fan won't need to be very large lol.

Tell you what Antler, grab one of these or something similar and you should be fine: https://www.amazon.com/gp/product/B072N332WT/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
Judging from the size and complexity of what you're trying to do, this might be a good option for you.
It's just a booster fan with 100cfm, run it w/ passive intake. You could put a 4" carbon filter with it if smell will be an issue, but I can't say what you would really accomplish for odor control with that setup.
What are you planning to use for lighting?