How often should I be running my exhaust?

Is there a general rule of thumb about how often you should clean the air from the room?

24-7 to prevent powdery mildew during lights out and to kool during lights on

^^^^agreed 24/7

Does it matter that it will be strictly veg?

yeah you want to keep fresh air in there 24/7 humidity rises when the lights go out and you don't want problems starting like powdery mildue as mentioned by kanuck above

if you have a lights out time and REALLY want to shut it off you can while lights off for a bit.
but the exhaust is taking air out of your room wich causes fesh air to come in brining C02 and your plants need it to grow.

yeah im a 24/7 guy aswell although there is a formula reccommended something like u have your exhaust has to vent x3 the cubic measurement of your room every hour

i have to 24/7 as i have a humid grow space that has a gas heater in it (also adds moisture) beacuse my grow room too cold else

gl dude

Thanks guys, if anyone knows the formula mentioned I would be interested to see it.

its more for the fan your rooms L X W X H = room cubic footage, many will want a fan that can move the air 3 times a minute

so my veg room is 4 X 4X 8 = 128 a 400 cfm fan will do it nicely

Ah I see. I was originally thinking I would have the exhaust fan on a timer and have it come on and off but I will deff consider keeping it on 24/7 now.