a slowsand filter uses a bacteria layer to do the work, the rest ofthe sand at that time does nothing. a zigzag (like how donkey kong barrels go) path for water to follow with a dripping channel under neath that sends the 'clean' water off to the side. water is dropped high and waste water comes out the bottom, clean water comes out the bottom and to the side. for a sparger a series of wet socks attached to a centrifugal fan . these designs are ideas right now. the reason i wanna look into a sparger is to have a better carbon filter design for long life, even though my carbon filter seems to not ever die. (e, for small apartments, pot smokers, heavily used kitchens, womens bathrooms, etc... carbon filters will add many football feilds of surface area to your home in which these odors can stick, leaving your home smelling like nothing but the cigarette being smoked outside your window.