Fans ensure good air circulation, while activated carbon filters keep the air that leaves the box smelling fresh. (geekwrapped.com)
So like with activated carbon filters, the quality of water decreases with use. (chestsculpting.com)
Next, there's a 10 inch coconut shell activated carbon filter for chlorine and volatile organic chemicals, followed by an even finer carbon filter. (supernaturalacnetreatment.com)