7 A filter including a housing (2) having an inlet (4) connectable to an upstream pipe, and an outlet (6) connectable to a downstream pipe; and a stack of discs (20) disposed within the housing (2) for separating solid particles from a fluid flowing between the discs (20) from the upstream side of said stack to the downstream side thereof. The filter discs (20) have a large surface area of their side faces formed with grooves and a spacer member (22) interposed between each pair of adjacent filter discs (20), the spacer members (20) having surfaces contacting only a portion of the grooved faces of the filter discs (20) on the upstream side of the stack not contacted by the spacer members (22) to thereby form compartments (24) on the upstream side of the stack for accumulation of solid particles which settle in the grooves, edge filtering passageways along the upstream edges of the spacer members (22) in contact with the grooved faces of the filter discs (20), which passageways define the size of particles separated by the filter and further filtering passageways of large surface area in the compartments (24), these latter passageways extending between the particles settling in the grooves in the compartments (24) and through the grooves to the downstream side of the stack.