Best way to ventilate my tent..

Trying to figure out the best way to ventilate my tent, its a 4x8x6 and I'm currently running "2" 600's in there using a 6in. inline fan set to a temperature controller to cool the lights. The same fan is being used to pull air from the carbon filter. I understand I want negative pressure in the tent. (exhaust bigger than intake) but I'm feeling like my intake is slacking a little bit.
What size should my intake be? Im currently using a 6in. duct booster fan for my intake just because I had it lying around but I feel like thats really not enough. Im not asking you guys to post links on the exact fan to buy, just what kind of CFM should I be shooting for?
Sorry for the (nebbish) question I'm used to running co2 so intake was never really an issue. Current spot co2 is a little bit of a stealth issue..

Not sure if this helps but I use an 8" can fan 737 cfm for my srcubbing and hood cooling on my 4x8 tent. Thing practically sucked the walls in as I only do a passive intake. Got a fan speed controller and everything is good. I still have plenty of air circulation and not even half as loud. What I am saying is that i don't think ya really need a fan on intake unless you are pulling intake air from somewhere not close to the tent and just control the exhaust fan.

I see you say you use it for temp also so may not have helped but hey I tried.

I have never used an intake fan. I've set up rooms and tents, always with negative pressure if not sealed, and never needed an intake fan as long as the exhaust fan was adequate and the intake opening area was twice the exhaust opening area.

Intake fans are the fastest, easiest way to positive pressure.

Inline fans says nothing. Your booster is inline, too. So is my mixed vent. What type of fan, what CFM?

If you have a ventilation question, it's answer is probably found in Ventilation 101