Negative pressure

What is the idea of negative pressure in a grow tent accomplishing. Is it to help keep smell contained or is it beneficial to growth. I have seen it mentioned several times in different threads. I’m just not clear on why it may be important.

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@Bulldognuts The negative pressure in the tent lets you know none of the odor escapes the tent it’s all going out exhaust fan also with negative pressure with Pass through hole open at bottom of tent you’re pulling in fresh air and exhausting hot stale air.


Air exchanges (cycle of fresh air through a building, room, or tent) are important for growth. That doesn’t necessarily have to use a negative pressure deficit.

Positive pressure can also be beneficial, if you’re concerned about keeping your environment more sterile. A medical tent or MilSpec food tent will utilize positive pressure.

In negative pressure, a swing door might be hard to open. In positive pressure, a swing door might be hard to close.

With a tent in a finished space of a home, negative pressure might be best as it helps contain odor when properly set up. In a basement or garage, maybe mold spores and pests are more of a concern, so you’d select positive pressure.

Does that make sense?


I can’t think of a single reason why that makes sense, unless you’re filtering, and using UV light to kill anything coming in through your intake fan. Otherwise you’re still pumping in what you’re trying to keep out. @KeystoneCops
Just my thoughts.

Negative pressure is essentially for smell, and negative pressure in the tent keeps the smell going through the carbon filter.
If you don’t care about smells, you don’t need negative pressure, but typically it’s still set up this way to keep airflow going through the tent. You still need air exchange to keep humidity under control, and bring fresh air in.



You should be filtering the air coming into your grow space. I mean, it’s optimal. And I’d aim for MERV13. UV light seems excessive, and the spectrum that’s most useful for sterilization is super harmful to humans, so…

If you’re in a legal area, and you’re concerned about pests and or mold, positive pressure is a useful tool.