At one time, a large mechanical filter designed to clear the air of cigarette smoke was located on the lower level.
It was often used in mechanical filters before quartz.
The components of a mechanical filter are all directly analogous to the various elements found in electrical circuits.
This makes it possible to apply electrical network analysis and filter design methods to mechanical filters.
Another common piezoelectric material is quartz, which has also been used in mechanical filters.
Pumps, mechanical filters, and disinfectants are often used to filter the water.
These are thoroughly described in the article on mechanical filters.
Another problem was that the mechanical filter made them flicker unless very high refresh rates were used.
The mechanical filter should be backwashed or cleaned out often.
Because of this, electric filters are sometimes made by first making a mechanical filter.