Ok so I have a 5x5 tent with a 1000 watt hps. I have a 6 inch 440 cfm exhaust fan that runs through a cool tube and then outside. Currently I am just opening the 3 or 4 intake flaps around the tent and letting the 6 inch suck fresh air in. Question is should I have a intake fan bringing fresh air in? If so how many cfm. My temps and humidity are pretty much perfect.
That said i like to use about half to 2/3 the cfm of the exhaust for intake fans. They do reduce the stress on the exhaust fan and in my room i am pushing air conditioned air in to the flower room from the veg/ lung room next room over. Passive intake was not enough.
Negative pressure will force your exhaust fan to work harder than it needs too. Unless you’re able to leave the flaps open during lights off. I had to add an intake fan dispute what everyone told me. It all comes down to what you’re needs are like chemistry said.
Pulling out 1000, put back 1000... Having said that im in ur boat, my tents main zip is open and shits sucked in like a crack junkie coz my exhaust is over kill and i don't have an intake at all just 1 standing fan in the room