Multi-Media water filtration system

Multi-media water filters typically utilize three layers of media for multimedia filtration: Activated Carbon, Silica sand and gravel. These media are often chosen for use in multi media filters due to the distinct differences in their densities. Anthracite is the lightest filtration media per unit volume, followed by sand, and then gravel.

The idea behind using media with differing masses is that during back washing the lightest media with the largest particles (anthracite) will naturally stratify at the top of the filter, while the intermediate sized media (sand) will settle in the middle, and the heaviest media with the smallest particles (garnet) will settle to the bottom.