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Quite closely related to deep-bed filtration in principle is precoat filtration, which uses a bed of inert solids formed on the upstream surface of a relatively coarse filter medium to act as the actual medium. The most popular solids for this purpose are kieselguhr (diatomaceous earth) and perlite. These can only be used where the collected solids are not wanted for subsequent treatment.

Kieselguhr is also used as a filter medium in its own right, again for clarification duties, being used by itself or in combination with cellulose fibres, as in the filter sheets used for beer clarification.