Description: Made of highly compressed diatomaceous ceramic. It has a pore size of 0.2 to 0.5 microns, which is small enough to trap bacteria (like cholera and typhoid), silt, and rust.
Key Benefit: It acts as a "3D sieve," removing contaminants before they reach the carbon filter.
Maintenance: It can be cleaned by gently scrubbing the surface with a scouring pad when it turns brown from sediment.