Clear-Fast Filter The CLEAR-FAST filter uses diatomaceous earth (filter powder) as the filtration media to filter liquids down to 1/2 micron. The CLEAR-FAST works well with ceramic and carbide grinding coolants. Many customers use a DEEP-BED as a pre-filter and the CLEAR-FAST to polish the coolant. We offer free testing to determine the suitability of your coolant and the CLEAR-FAST filter.