Diatomaceous Earth (DE) / Perlite filters have superior filtration compared to cartridge or sand filters and can filter down to 1-5 microns.
Diatomaceous Earth consists of fossilised diatoms, microscopic dead algae that combine with clay and minerals over time. When used for filtration, it acts like tiny sponges which can filter out very fine suspended particles. Perlite can also be used as a Diatomaceous Earth replacement.