Many growers of medical marijuana absolutely love the smell of that sweet sweet ganja. However, that doesn't mean the neighbor likes that sweet aroma. They may take that smell as a strongly negative thing and could actually end up calling the police which would obviously create quite the headache for even the legal grower. I have heard countless stories of law enforcement taking legal grows because they didn't check first. This can end up being huge losses for the grower. Instead of worrying about the odor given off by your flowering plants, it is generally recommended to use a carbon filter or something similar to remove the odor from the air.

Carbon filters use activated charcoal to clean the air of odors. Activated carbon is "activated" by an oxygenation process. The oxygen activates the charcoal by opening up millions of tiny pores between the carbon atoms. This opens up a lot of space for the carbon to "suck up" the odors put off by marijuana. This chemical bonding of the carbon atoms to the odor removes the odor from the air completely and traps it chemically to the surface of the charcoal.

Carbon filters come in a wide range of sizes. They can be several feet tall with a large diameter or they can be the size of a large cup. This obviously depends on the amount of air that you need to scrub clean. The more area and the more air you are moving (CFM), the bigger carbon filter you will need to properly filter the air of those unwanted odors. Most of the time the carbon filters you will end up buying are actually very simple pieces of equipment. They are typically in a cylindrical form with an open core. But within the walls of the filter, it is packed with that activated charcoal.

It is generally recommended to hook up your carbon filter inside your grow environment. This is to ensure that the air is being sucked through the filter, rather than pushed through. If you put the filter on the end of your exhaust where the air is being pushed out, it will keep the odor from getting out, but it will also severely limit your exhaust air flow. By sucking the air through the filter first, then exhausting it, you are able to maintain almost the same airflow as you had before adding the filter.

For a cool Homemade Carbon Filter, click this link. For any other homemade hydroponic system, click this link.