The invention relates to a filter, comprising a filter medium (10), which during operation is used to clean fluid, particularly in the form of hydraulic fluid, wherein the filter medium (10) is made of a material the potential difference to the fluid to be cleaned is low. The invention further relates to filter solutions, wherein parts of the filter medium (10) have different potentials with respect to each other and/or the fluid to be cleaned such that they cancel each other at least partially, or wherein specific dissipation is aspired, or wherein a return of electric charge to the associated filter medium (10) is provided, using a charge equalization situation.