Negative pressure in tent

Hello !

Im finalizing my grow tent setup but have a question on exhaust/intake fan.. my tent is 4x4x7

currently i have 6inch 390cfm exhaust fan (connected to carbonfilter 6 inch) and 4inch 190cfm intake fan.. when I start the exhaust fan to minimum and put the small one to maximum I still have negative pressure in the tent..

Im wondering if I should leave them running like that or if I should get a 6inch intake fan as well (same as exhaust) and play with the controler to create juste a little negative pressure as required (rather than leaving the 4inch to max speed) .. but not too much? Ive try to read on the subject and some people claim ratio should be 2:1 some claim you should change the grow tent air at least every 3-5 minutes some other I read states 2-3 times every minutes.. it gets confusing.. my understanding is negative pressure is not a bad thing but just trying to see if a 6inch intake rather than my current 4inch would be better or if any if you have some suggestions for this part?

I think in terms of CFM im good so just a matter of knowing if I should do something better

Thanks

Leave both running & see where your temp settles to. Negative pressure insures no orders escapes the tent, if you're worried about that. If it keeps the heat under control, run it!

upnsmoke13 said:

Leave both running & see where your temp settles to. Negative pressure insures no orders escapes the tent, if you're worried about that. If it keeps the heat under control, run it!

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Im just worried to put too much pressure on the 4inch intake running at max speed for long period of time while the exhaust is at minimum and still blow out more air.. so if I get a 6inch intake I can run the exhaust at mid speed and intake at low thus reducing the pressure on the intake while maintaining negative pressure in the grow tent..

I think it make sense but im still hesitating

There is no need for an intake fan. All you need is a hole that allows passive intake. If you place both your fans as exhaust you will have more ventilation than if you place one intake and one exhaust.

zem said:

There is no need for an intake fan. All you need is a hole that allows passive intake. If you place both your fans as exhaust you will have more ventilation than if you place one intake and one exhaust.

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I guess it kind of make sense.. I could use 2 passive hole at the bottom of the tent to get new fresh air in while only the exhaust is working.. ill try it out and see if it works good.. I think the intake fan may help lowering the temp as I can have it further in the room but beside that it may just not be required and could save 100$! Thanks for the comment ill test it