There are two kinds of DE replacements...One is cellulose fiber and the other is perlite, a type of volcanic rock. I have no info on the filtering ability of either as to how small they will filter. I know the cellulose one can be used with cartridge filters since it doesn't clog the reemay polyester filter material. The perlite is still a silceous (glass) rock so it still might be dangerous to inhale. don't really know.