Abstract: The present invention is directed to secondary filtration apparatus used in combination with a full flow filter of the type commonly used in series with a use device. The secondary filter system includes within a base an orifice for limiting fluid flow and a pressure reducing and relieving device for maintaining a pressure level to the secondary filter thereby allowing use of a filter element of much smaller porosity than the full flow filter element. Much greater cleansing of the fluid is achieved thereby increasing the lifetime of the use device and reducing maintenance costs.