The most common, and IMO most effective, form of odor control is the Carbon filter aka charcoal filter aka scrubber. A Carbon filter is a metal canister filled with charcoal (carbon) designed for the specific use of air filtration. Some filters come with a flange already connected to the filter itself, but you may have to buy one separate depending on brand. The filter can be used either as a stand alone scrubber or attached to light hoods designed to be ''air cooled''. Sizing your filter is simple. Measure your grow space and multiply. Length X Width X Height, which gives you the cubic feet of your space. You will need all three measurements to correctly size your filter. For our friends using the metric system, the same goes for you. You're going to want to clean, or ''scrub'', the air in your room at least 3-5 times per minute. Some growers scrub more, but IMO the minimum is 3 times per minute. The CFM rating for your filter should be stamped on the filter somewhere, or ask the guy at the gardening store. There are also good DIY threads on building your own filter if you search this forum. The fan size for your filter should be close to the same CFMs the filter is rated for. If the fan size is off either way, more or less CFMs, the filter wont be cleaning the air effectively. Air flow should be sucking through the filter instead of pushing air through it. Here's an example of how I set up my filter. I attached my 6inch inline fan to the 6inch flange using 6inch ducting and 2 drive clamps.