Which type of filters typically utilize dual or multi-media layers?

High-rate filters are designed to handle large volumes of water efficiently and are often equipped with dual or multi-media layers. The use of multiple media allows for better filtration by providing different materials that can capture particles of varying sizes. Typically, a heavier media is placed at the bottom, while lighter media lies above it. This setup enhances the filter's performance by allowing it to trap a wider range of contaminants and improve the overall clarity of the water.

Additionally, multi-media filters can reduce the frequency of backwashing compared to single media layers, as the different materials allow for a more balanced flow and less clogging. This capability helps maintain a more consistent filtration rate and improves overall operational efficiency, making high-rate filters a popular choice in modern water treatment facilities.