I have a 4” fan filter for my 2x2.5 tent, but uograding a bit to a 3x3. Do I need to go with a 4 “ or a 6”? This is a gorilla tent with a 2 foot vertical extention kit.
Depends on if you live in a cold or hot climate.
But yes it's certainly better to run bigger and turn it down with a good speed controller.
Least better for sound
A 4" fan in a 3x3 tent works fine
In my cool basement environment, my 4" AC fan rarely runs higher than 50%; a 6" fan wouldn't wouldn't provide any improvement
Your mileage may vary
A hot environment requiring more airflow may benefit from a larger fan, if nothing else, to reduce noise (a bigger fan runs slower for same cfm)
A 4" fan in a 3x3 tent works fine
In my cool basement environment, my 4" AC fan rarely runs higher than 50%; a 6" fan wouldn't wouldn't provide any improvement
Your mileage may vary
A hot environment requiring more airflow may benefit from a larger fan, if nothing else, to reduce noise (a bigger fan runs slower for same cfm)
always keep in mind with ventilation just because you have dialed in temperature and humidity and have gotten the lowest fan speed possible-- you should still get a CO2 monitor if trying to lower fan speeds for sound. A co2 monitor will ensure that you are ventilating adequately, and inkbird makes an affordable wifi co2 logger that I love. If you really want to spend some money try out the pulse pro! Sometimes you just need a bit of fresh air to help add the co2 you need into a space, but most of the time the co2 you breathe in your house will supply the plants with what they need as long as air is circulated throughout the house.
I was sold on the ac infinity fans on the idea that you can automate on temp and humidity, but I would really love it if it had a way to integrate a co2 meter.
people ask why are some people recommending high PPM for feed. Well it comes down to enough light, combined with proper ventilation (temp+humidity) and nutrients to get as much as possible per square foot. It is very hard to control all the variables in a grow, but as you get better at controlling all of these the plants will eat more and more