Ventilation help!!

I am a first time grower and I was wondering if I need a exhaust fan or not. my setup is a 18 gallon Rubbermaid dwc in a 3' x 3' x 5' grow tent with a 600 w mh. I have my tent in my basement and it stays about 60-65°f. any advice would be great.

yes you will need exhaust fan or your plants will be cooked

definatly need an exhaust fan, id recomend a cool tube as well.

Yes what they said....do you have any fans in there or what ?

you most certainly will NEED an exhaust fan and carbon filter, if you don't want the smell to escape. When you flip them to flower and they really start to bud, they will stink, bad.
you also would benefit from a small clip-on circulation fan inside your tent. This will keep air moving around your plants, which is very important. It will also help to strengthen your stems through the subtle movement.

and a friendly word of advice I wish someone told me... being your first grow, make sure you keep an eye on your vertical space, especially when you flip to 12/12. The "stretch" that takes place can double, sometimes even triple, a plants size... I've had to chop off more than one khola because I under estimated the stretch and when the plant started to stretch, it grew up into the light.

Yes and cool tube or enclosed hood..

Of course you do, you will be introducing a heat source. If the heat cannot go anywhere it will get hotter and hotter and hotter.