CFM size for tent size and hps

Just purchased a 390 cfm inline vivosun fan for a 3x3 tent that is 400hps air cooled hood. Is this the right size? It seems like its barely coming out of the ducting that isn't running more than maybe 6 feet. I had the green hydrofarm 400cfm and its blowing a lot out of the end of the ducting. This hydrofarm is way more than 10 cfm or the vivosun isn't really 390.

Depends on the static pressure I think, some fans push or pull better due to the blade type and orientation.

As for how much cfm. It depends on your base ambient temps and how much above that your ideal temperature is.

If your at 65f and want to be 80f it takes a lot less than if your at 73f and want to be at 80f.

Think my veg tent is 120-180cfm with 400w mh.
Manages easy but it's a box fan and handles all resistance really well.

Meast21 said:

Just purchased a 390 cfm inline vivosun fan for a 3x3 tent that is 400hps air cooled hood. Is this the right size? It seems like its barely coming out of the ducting that isn't running more than maybe 6 feet. I had the green hydrofarm 400cfm and its blowing a lot out of the end of the ducting. This hydrofarm is way more than 10 cfm or the vivosun isn't really 390.

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I try to explain the static pressure thing all the time to people. The green monsters are kick ass. If you want a high end version of those get the Vortex VTX. A favorite of many.. Vortex is the only company I've seen that lists specific static pressure ratings. I have both and they rock.

Look at the difference between the S-Line and the VTX for static pressure ratings.

Meast21 said:

Just purchased a 390 cfm inline vivosun fan for a 3x3 tent that is 400hps air cooled hood. Is this the right size? It seems like its barely coming out of the ducting that isn't running more than maybe 6 feet. I had the green hydrofarm 400cfm and its blowing a lot out of the end of the ducting. This hydrofarm is way more than 10 cfm or the vivosun isn't really 390.

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If you are using the fan to keep things cool it should definitely help. But if you are planning on using carbon filtration, you have way too many CFM. Carbon needs proper "dwell time" of the odor within the carbon to scrub the odor. Usually around 15 ACH.

To find out how many ACH you currently have you need to multiply your fan cfm (390) x 60 and divide by the volume.

390 x 60 = 23,400 / 54 = 433 ACH.

McStrats said:

If you are using the fan to keep things cool it should definitely help. But if you are planning on using carbon filtration, you have way too many CFM. Carbon needs proper "dwell time" of the odor within the carbon to scrub the odor. Usually around 15 ACH.

To find out how many ACH you currently have you need to multiply your fan cfm (390) x 60 and divide by the volume.

390 x 60 = 23,400 / 54 = 433 ACH.

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Thank you for the input, i had no clue. This is why I love RIU

EvilJ said:

Thank you for the input, i had no clue. This is why I love RIU

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You are most welcome! Glad I could help