Carbon Filters, How good do they work?

Hey everyone. I'm just wondering how well carbon filters actually work. I'm going to be setting up a 20 plant SOG (5 plants for each stage) In a separate bedroom and I'm curious to know exactly how effective these things are. Wether it's a store bought or a DIY. how effectively do they eliminate odor inside and outside the room. I'd appreciate your feedback, thanks.

All I know is my store bought can filter setup gets rid of at least 99% of the smell, you just need to replace filter every so often.

Damn well. Damn, damn well.