Exhaust questions - Timing etc...

Guess ill start off with specifications...

80-100F OUTSIDE during spring/summer. 25-50% humidity OUTSIDE.

My room is 8'6"Wx12'Lx8'H and I have a 750 cfm 8" vortex exhaust. I have a 4" passive intake and an AC for temp control. I also have a dehumidifier with humidistat that will auto kick on if humidity gets too high so I can leave that running without it dehumidifying 24/7. 2 oscilating fans at opposite ends.

Temps are always 73-80*F INSIDE. Humidity 25-45% INSIDE.

My question is how much do I actually have to run my exhaust to replace the air? I keep getting all sorts of different answers for this which is why I included my specifications. Ive already completed a grow and I had it on 24/7 but just wondered if I could cut down the amount of exhaust time so I can cut down on AC/electricity cost. Or since I have the intake/exhaust well placed at opposite ends of each other, am I not really sucking up all that cold air? I considered hooking up the exhaust to a thermostat but then wondered if the stale air would be replaced during the dark period when the temps are lower?

Or if you wish just explain what the ideal set up is for the exhaust with everything in my specs I would appreciate that too!

Thanks in advance!

If it's 100 where you live I suspect that you have central air...right? I also suspect that it runs a fair amount of the day, mine does. It is exchanging the air in there every time it is running, your temps are in the sweet spot. You have fans moving the room air around. I would try and run it with out the vortex, I suspect that you will be fine.

I have a wall AC unit 12000 btu that pulls air from in the room, not a central air. Forgot to specify that sorry .