Garnet sand is used at the bottom medium in multimedia filters. What characteristics does garnet sand have compared to the other sand in the filter?

Garnet sand is used at the bottom medium in multimedia filters. What characteristics does garnet sand have compared to the other sand in the filter?

• A. finer and greater density
• B. coarser and greater density
• C. finer and lower density
• D. coarser and lower density

Answer: (A)

In multimedia filters, the bottom layer is made denser and finer than the layers above to capture smaller particles and keep the bed stable during flow and backwashing. Garnet fits this role because it is much denser than the sand in the middle layer and is typically finer in grain size. That combination creates a denser, finer bottom bed that traps fine particulates more effectively and helps maintain clear separation between layers, improving overall filtration performance. If the bottom layer were coarser or less dense, smaller particles could pass through more easily and the bed could mix or channel under flow.

In multimedia filters, the bottom layer is made denser and finer than the layers above to capture smaller particles and keep the bed stable during flow and backwashing. Garnet fits this role because it is much denser than the sand in the middle layer and is typically finer in grain size. That combination creates a denser, finer bottom bed that traps fine particulates more effectively and helps maintain clear separation between layers, improving overall filtration performance. If the bottom layer were coarser or less dense, smaller particles could pass through more easily and the bed could mix or channel under flow.