Carbon filters are the mainstay of modern scent neutralisation of almost all indoor cannabis cultivation.
Due to both its straightforward use and high efficiency, they are being used both in amateur DIY setups as well as professional commercial cannabis plantations.
The idea behind carbon filtering is for the activated carbon that sits in the filter to catch all of the aroma from the air that is being fanned out of the grow area.
Since activated carbon has limited capacity of capturing the particles responsible for the characteristic scent of ripening marijuana, they have to be replaced every now and then.
Depending on the quality of the filter and the required level of smell neutralisation, growers tend to change their filters after between one cycle and one year.
Carbon filters are rather bulky - those meant to serve bigger grow areas can easily exceed 100 kg, and even the smallest don't go below several kilos.
The filter should be fitted to the exhaust fan used, both in terms of the diamater (100, 125, 150, 160 or 200mm) and power - preferably neither stronger, nor lighter then then fan's power.
While in some of the filters it is technically possible to change the activated carbon without replacing the whole thing, the DIY methods are usually not recommended by the producer and may significantly reduce the longevity and efficiency.