Ventilation query for closet grow

Ok, so i've got my babies at week 4 now, ad i've been modifying the closet to suit the plant, I have a ventilation port at the bottom of the closet that I have cleaned out so fresh air can come through, the top of the closet has no top as such so heat can rise and escape. I Have a good sized fan in there moving the air around also. My question is do I need to purchase something to pull the air on and out or will the job of ventilation be completed now? Temps are fine btw.

If you point one of the fans blowing up you'd likely be ok- as long as this is just your veg closet.. If not you may want to buy some poly and vapor barrier tape, and a small duct booster fan or something, and a carbon scrubber to fit.
In veg you do want to draw fresh air into the space somehow. Plants give off oxygen but need to take in co2 for photosynthesis to occur. Your fans will help move around the co2 and o2 but it won't be as good as fresh air brought in.
If you plan on flowering in the same closet, unless you're out in the boonies with no visitors , smell will be an issue down the road, so you may as well get something that will do both.
Just trying to help

Thanks for the advice, I'll be finishing off in the closet and I hope it doesn't smell to bad lol if I get a inlet and an outlet and fit them in the vent with a carbon scrubber will this solve the problem?

Basically if you have a hole - that's an intake. (called passive intake) which is usually fine in a closet without a problem.
For flower it can get REALLY smelly depending on the strain... You'll want something at least in mind for that day you open your front door and it smells like a skunk died. I've made my own carbon filters.. They work just fine, but you aren't saving a whole lot over buying a pre-made one if you shop around. Should you decide to make the investment, make sure your exhaust is bigger than you need for the space.
Take it easy...

Thanks cowell, Last question, If I buy the carbon filter do I need to make it air tight? or will it scrub the air enough to prevent smell? I dont mind a bit of smell I smoke it every day anyway and my house always smells PENGY lol a nice PENGY of course

Deffo get a carbon filter and fan, i use a 6" in my closet with a 600w hps light, check out my sig.

http://www.amazon.com/LED-Wholesalers-GYO2402-Hydroponic-Booster/dp/B003YFADW8/ref=sr_1_10?ie=UTF8&qid=1334864214&sr=8-10

check it! i got 2 of those for my 3x3 tent intake and exaust ..i dont have a a filter..400w..sometimes with the light on the air is moving too quickly it get under 75F so on cool days i turn the intake off..so really if u grab 1 of those ull be golden and its only $25 and its reliable

It doesn't have to be "air tight"... What will happen is you'll try your best to make it air tight... Then with your exhaust fan you will draw air IN through any holes you missed. It will still contain the smell, because no air is leaving through anything except the filter.. If you do have any questions- just ask, lots of guys around that want to help out

Thanks again man +rep for your time and advice

no worries, we've all been there.. First time you flower you will understand just how stinky it can be.