In a multi-media filter, which media is the largest and least dense?

In a multi-media filter, anthracite is recognized as the largest and least dense media among the options provided. Anthracite is a type of coal that is characterized by its high carbon content and is used in filtration systems due to its buoyancy and low density as compared to other more compact media like sand or zeolite. Its larger size also facilitates better flow dynamics, allowing for effective treatment of water and other fluids by promoting both physical and chemical filtration processes.

In multi-media filters, the arrangement typically starts with larger, less dense particles at the top, allowing for easier passage and initial filtration of larger particles before moving down to finer media. This layering is crucial for optimizing the filtration process. Anthracite fits this profile, as its lower density enables it to float above the more compact media, enhancing filtration efficiency while reducing the likelihood of clogging.

Other options like garnet, sand, and zeolite have their specific uses and characteristics but do not meet the criteria of being the largest and least dense compared to anthracite in the context of multi-media filtration systems.