NOVELTY - The lead through comprises a first element (12) that is arranged in fluid tight connection with a roof of a fluid housing tank and presents a central opening and an axially extending centre axis, a second element (13) that is arranged in fluid tight connection with a mixer assembly and presents the central opening and the axially extending centre axis, a unit for making an interface fluid tight located at the interface between the first element and the second element, and three positioning members arranged to determine the mutual positions of the first and second elements in the axial direction.    USE - The lead through is useful for fluid tight connection of a mixer assembly for agitating excrements such as feces, sludge or waste water to a roof of a fluid housing digestion tank to extract methane gas and carbon dioxide.    ADVANTAGE - The lead through ensures effective fluid tight connection of the mixer assembly with improved quantities of various gases, and can be easily adjusted by an individual without any auxiliary equipment such as cranes.    DETAILED DESCRIPTION - The lead through comprises a first element (12) that is arranged in fluid tight connection with a roof of a fluid housing tank and presents a central opening and an axially extending centre axis, a second element (13) that is arranged in fluid tight connection with a mixer assembly and presents the central opening and the axially extending centre axis, a unit for making an interface fluid tight located at the interface between the first element and the second element, three positioning members arranged to determine the mutual positions of the first and second elements in the axial direction, and two of the positioning members constituted by mutually independent adjustment members (24) in relation to the fluid housing tank. The extension of the centre axis of the second element is adjusted in relation to the extension of the centre axis of the first element. The first element and the second element are telescopically arranged in relation to each other in the axial direction. The unit for making the interface fluid tight comprises a circumferentially extending sealing ring that abuts an inner surface of the first element and an outer surface of the second element, and a circumferentially extending fluid seal. Each adjustment member comprises a first wedge element, a second wedge element cooperating with the first wedge element and an adjustment unit that is maneuverable in order to increase and decrease, respectively, the axial height of the adjustment member. The positioning members are located on the opposite side of the unit for making the interface fluid tight. The first wedge element abuts an upwardly facing surface of the first element, and that the second wedge element abuts a downwardly facing surface of the second element. The adjustment unit comprises a first screw maneuverable in order to increase the axial height of the adjustment member and a second screw maneuverable in order to decrease the axial height of the adjustment member.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic side view of a lead through.    First element (12)    Second element (13)    Axially extending tube shaped body (15, 20)    Number of stiffeners (17)    Adjustment members. (24)