A carbon filter is a round, hollow device with a membrane that contains activated charcoal (carbon). Dirty air passes through the filter and clean, odorless air exits. Carbon filters are effective, inexpensive and require minimum maintenance.
Activated charcoal has micro-porosity, with a huge surface area. Usually the activated carbon will require changing every 12 to 18 months.
It is recommended that air should be exchanged in the grow space every 5 minutes.