First, a little background. I have a 4' wide, 20" deep, 6' tall cabinet inside of a closet with sliding doors. The grow chamber is 5' tall and there is a sealed off shelf at the top. There is a passive intake on the lower right side of the cabinet, and a fan draws air out of the grow chamber into the shelf area at the top left. The exhaust travels the length of the cabinet and exits on the top right. A carboard "duct" then chanels the exhaust to the left side of the cabinet (on the outside). The doors of the closet are left cracked about 6" on each side.
Odor control:
1. Strains. Two NL (Nirvana "pure indica" variety) and three Cindy 99's (the F2 available on Seeds Direct). These are relatively low odor plants. The two NL's are vastly different phenotypes; one smells a bit skunky at times and looks vaguely sativa for an NL, while the other barely smells at all (and has the broadest leaves you've ever seen). The Cindy's have a slightly fruity-sweet odor, but don't really smell obviously like weed.
2. Activated carbon furnace filter (available at a hardware store for about $8) in the exhaust shelf.
3. Holmes air purifier (available at Wal-Mart for about $30) with hepa/carbon filtration and ionizer. This sits at the end of the cardboard duct.
4. Sharper Image mini-size ionizer sitting on top of the cabinet.
5. Baking soda. Two sitting among the plants inside the cabinet and one in the exhaust system.
6. Renuzit odor-absorbing gel pod (available at the grocery store for a few bucks). This is sitting in the room a few feet away from the closet.
7. Glade plug-in in the apartment's living room (just to make sure anything leaking out of the back room is covered).
This may seem like odor-control overkill, but I've figured that odor is my primary risk for getting pinched
Interestingly, even this level of odor security doesn't always eliminate absolutely all traces of weed smell in the apartment. I find the plants can overpower my myriad levels of security after a feeding/watering. The smell is faint and probably wouldn't be noticed by a "civilian", but I'm completely paranoid and end up spending about 5 minutes every morning sniffing the air to catch a whiff of that tell-tale scent.
Did I mention, I just started flowering yesterday; this smell has been during veg?