Setting up new room

I have a 4.75^2 x 8ft room to use. I will be setting up a veg cab after getting my grow going. I will be using a 600whps to flower with. I have a lumatek dimmabla ballast, 6" air cooled reflector, carbon filter. I was thinking of running a 6"y and have my vortex 449cfm inline fan pull air through the filter and out of the room and also pull the heat off the hood. My questions are is 449 CFm too much and how many CFm would be an adequate amount for proper air exchange. Or how would you change the ventilation setup? I will be mainlining and scrogging 2-4 plants under this setup

You don't need to 'y' it. Filter>Hood>Exhaust fan/out
5x5x8 = 200 cubic feet. So with that fan you will be turning the air twice/minute. You may need a speed controller for you fan to dial it down.

thanks, that makes more sense. Is there an exchange rate formula I should go by on how often the air should be exchanged in the room

Well you just wanna match it up. So the cfm of the filter should be 200 or above, because that is the space you are working with. Then you match the fan to the filter. So like 1/minute. I'd say you're good as long as your filter is the correct rating and perhaps you dial your fan down. You don't want the fan to pull too fast through the filter, or it will not be as effective.

Would 3 fans be a better option, one strictly for Cooling the lights, one for exhaust and one for intake? And of course oscillating fans for circulation

Your fan's 449 cfm should take care of the cooling and the exhaust.....Filter>hood>exhaust fan. As long as you have an opening for passive intake you should be fine. I wouldn't worry about it unless it becomes an issue. Then you can add an intake if needed.

10-4, thanks for the input