OK, first of all if you want to get the best answers to you questions post as many details as you can about your grow as your not giving us very much to work with IE: Are you using a T5, MH, HPS or all three? What's the wattage? How many plants will you be growing? What is the ambient temp of the room the tent will be in? What's your budget? All these things will help us to help you. I'll do what I can with what I have to answer your questions. While T5's produce a lot less heat than HID (MH/HPS) they still produce enough heat that It'll need some ventilation, if your only using a T5 you could get away with just a 6" booster fan from Home Depot (you will also need a fan blowing on the plants of course), however if your using MH/HPS it will depend on the wattage, a 250W-400W MH/HPS will require at least a 4" inline fan or a 6" booster fan, a 600W-1000W MH/HPS will require at least a 6"-8" inline fan, for your size tent (this will depend on how many plants you intend to grow) I would recommend a 400W or 600W MH/HPS, I would also recommend that you do SOG (Sea Of Green) where you keep the plants short, about a foot or so, so you basically end up with one cola per plant, with this method you will yield less each harvest but you will harvest more often (and harvesting is the funnest most rewarding part, at least for me) so you end up with more weight in the long run. As for the carbon filter you won't need a very big one so I would recommend you DIY one your self, look up DIY carbon filter either here or on Google or even ask an employee at your local hydro shop, mine sells everything you need to build your own at a fraction of the price of a new pre -built one. Post back with more details regarding your grow so I can assess how close I am with my recommendations, hope this helps, keep us posted.