Media Support Gravel

Media support gravel consists of carefully sized, washed, and graded gravel or crushed stone particles that serve as a structural support layer in multi-media filtration systems. This layer is positioned beneath the primary filtration media (such as anthracite, sand, or garnet) to provide uniform hydraulic distribution, prevent the loss of finer media into underdrains, and maintain the integrity of the filter bed during backwashing and operation. The gravel is selected based on specific size gradations to create a stable, porous foundation that supports efficient filtration while minimizing pressure drop.

The working principle of media support gravel involves creating a stable, graded layer that supports the primary filtration media above it. During filtration, water flows downward through the media layers, and the gravel layer ensures even distribution across the filter bed, preventing channeling and optimizing contact time. During backwashing, the gravel layer prevents finer media from being washed into the underdrain system while allowing effective cleaning through fluidization. The gradation from coarse at the bottom to fine at the top provides mechanical stability and maintains separation between media types.