Abstract: A weir assembly is disclosed in which the size and shape of the opening can be easily changed, by utilizing a sizing insert system. In one embodiment, the sizing insert comprises a mechanical iris. The position of the opening is easily adjustable by utilizing at least one positioning stage that is fastened to the sizing insert. Spring plungers are utilized for retention of the transparent weir plate within the vertical channels of a water trough. A center-finder is utilized to approximately position the opening in relation to an extrusion die.

Abstract: Antimicrobial polymeric tubing is disclosed comprising a polymer compounded with a silver ion-emitting additive. In a second embodiment, the tubing is coextruded, and the silver ion-emitting additive is compounded only with the polymer located on the interior of the tube.