I use the 6"x16" Phresh carbon filter and it works great no smells at all outside the grow cabinet, not that I have too but I replace it after every grow which is about every 4-5 months... At $69 its just worth it to me to never have to worry about it failing and getting caught by the smell patrol, but if you can get a year more power to ya
I have 2 phresh filters. The smaller one has almost 2 years and it's still better then a new low budget one. I have tested that few months ago. The store I shop in don't have it anymore, they only have the above mentioned, but I'll order from elsewhere.