Greensand filter: The filter body was made of a 70 cm
long Plexiglas cylinder of 20 cm inside diameter and 1
cm wall thickness (Fig. 9). A circular plate of 22 cm
diameter and 1 cm thickness was glued to the bottom of
the cylinder. A 2.5 cm diameter plastic fitting, threaded
into the center of the plate, was used as the outlet.