I live in a house with 2 other people so I'm trying to keep this on the low (I own the place they rent off me)
I'm planning on growing in a cardboard box in my wardrobe
would I be able to grow without my house mates knowing
could I make a stealth box from cardboard
would a pc fan be enough for my carbon filter
if one pc fan wont work could I stack about 4 together for the carbon filter
how could I minimize noise like is there a foam or something i could use
thanks for all the help
What kind of wattage are you planning on using in this cardboard box? I ask this question mainly because of ventilation. If you are using a florescent light fixture you should be okay with a PC fan, but I recommend using two fans (one on each end of the filter). One fan might work, but keep in mind that the fan will lose some of it's capacity to move air because the air is being pulled through the filter. A fan on each end will help to move a little more air. Not only that but having some redundancy is wise just in case one of the fans fails. Good quality PC fans don't make much noise, so you shouldn't have a problem there.
Now, if you're planning on using a 250w light or more you will likely overheat the grow space unless the hood is air cooled. In that case, a PC fan will not do. You will need to get a higher wattage fan that is designed for this sort of thing. You can buy a "quiet" fan, but they're not exactly silent. Also, if you're using a higher wattage light I would not recommend using cardboard. You can probably get away with it with a florescent light, but 250w on up produce a LOT more heat. I concur with the other poster in that cardboard is a fire hazard. Don't be a cheapskate. Do it right or don't do it at all. I suggest investing in a real grow box like the one pictured below. There are all kinds of different sizes and configurations and the smaller boxes don't cost much. The ventilation holes and fixtures are built in and it zips up so you won't have issues with light leakage.
Of course you can grow without your housemates knowing as long as everything is put together properly.