German to English Science

Context is filtering of a mixture, during which reference is made to "Ist-Temperatur Filtrationsgegentank", "Filtratschlauch vom Gegentank demontieren und zu Kanal legen" and also in a table "Gewicht Überstand Gegentank (kg)". I am guessing it is a tank where the supernatant (Überstand?) is sent during the filtration process, and from which the tube is removed at the end and put into a disposal channel (zur Kanal legen?) to get rid of the supernatant? Would we call it a "counter tank"? Or an "opposing tank"? I can find no hits for any of these....thanks for any help!