Negative pressure; do you want it?

i was wondering if negative pressure is a positive thing? i don't have an intake fan only an exhaust but im running 1 fan and an ac unity on blast inside.

i was also wondering wtf is causing this negative pressure? earlier today it was doing fine no signs of this negative pressure but when the lights went out and i ran the AC longer the tent just started to bow inwards. im not really worried tent is fairly strong to manage the pressure and it's not like over kill pressure i just find it weird that it started to do this just now after i've had it on for almost the whole day now

its a good thing. means your tent is relatively air tight and you can control where it intakes from. also keeps the smells inside makes sure all your exhaust is goin thru a filter if you're using one. and any neg pressure created by just a fan is no prob for the tent or the plants

Yup. That's what you want

The only reason to maintain a negative pressure is for odor control, making sure any air that escapes the tent must go through the carbon filter.

Yep

I just finished vegging 3 plants in a 4x4 tent without an exhaust fan, only using oscillating fans to keep air moving, kept ports up top opened and intake flaps in bottom opened, no negative pressure, they grew the same as the bunch in the tent with exhaust, only one difference, as renfro said, smell

Reduced pressure will increase transpiration and transport of gasses through leaf membrane.
Look at high altitude studies surrounding co2 uptake, stoma densities, water capacity of the air.
Wheter these are significant to the avearge rec/personal grower remains a question.
I run my fans positive, I am already at 7700 feet a further reduction of pressure is not likely desired based on info I saw about photosynthesis being slowed at 0.5atm, my station pressure is about .75atm.