Fluid filtration devices and methods of filtering fluids are described. The devices generally include a housing, a hollow filter assembly, a rotating cleaning assembly and a device to measure the accumulation of solids in the filter housing. In some embodiments the accumulation of solids is measured by measuring the torque required to rotate the cleaning assembly. Torque may be measured directly, such as with a torque sensor, or indirectly, such as by measuring the current used by an electric motor to drive rotation of the cleaning assembly. In some embodiments a purge valve is opened to remove accumulated solids from the housing when a certain level of solids accumulation is detected.