I don't know if you meant it that way, but an "air tight room" isn't what you're going for. You still have to allow air into the room if you're going to be exhausting air from it. The trick is to have negative pressure so that 100% of the air leaving the grow space goes through the carbon filter.
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never 100%
your perceived magnitude and threshold of detection is not the same as someone who doesn't smoke and isn't around flowering plants
you can keep what you growPlug-in air fresheners have produced good results for me. They are designed to work with HEAT, so it makes them ideal for grow rooms. It mixes with the odour and transforms it into fragrance. I put the Plug-in on my 12/12 light relay, and this saves on refills. This might only work with light odour, but so far so good. From the results of my early tests, it seems to neutralise my odour problems.
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