A pump for an immersion circulator configured for use in a circulating bath containing a working fluid, said pump, comprising: a plurality of pump casings (60, 70, 80) including: a first metallic band defining a sidewall of one of said pump casings and having at least one tab projecting from a surface of said metallic band or at least one opening; and first and second plates (78, 79) disposed opposite one another, with said first metallic band being disposed therebetween, and with said first and second plates (78, 79) and said first metallic band jointly defining a first chamber of said pump casing which is configured to be filled with the working fluid when the pump casing is immersed in the working fluid, wherein at least one of said first or second plates (78, 79) includes at least one tab or at least one opening (78a, 79a) respectively cooperating with said at least one opening or said at least one tab, respectively, of said first metallic band so as to retain a formed shape of said first metallic band defining said pump casing; and a first impeller disposed within said first chamber; the pump being characterised in that further comprises: a second metallic band partially defining a second chamber of said pump; a third metallic band defining a third chamber of said pump with said third chamber being disposed between said first and second chambers and with a bent shape of said third chamber being retained through engagement of at least one tab and at least one opening (79a, 86a) at an interface between said third metallic band and said first or second plate (78, 79); and a second impeller disposed within said second chamber. a first metallic band defining a sidewall of one of said pump casings and having at least one tab projecting from a surface of said metallic band or at least one opening; and first and second plates (78, 79) disposed opposite one another, with said first metallic band being disposed therebetween, and with said first and second plates (78, 79) and said first metallic band jointly defining a first chamber of said pump casing which is configured to be filled with the working fluid when the pump casing is immersed in the working fluid, wherein at least one of said first or second plates (78, 79) includes at least one tab or at least one opening (78a, 79a) respectively cooperating with said at least one opening or said at least one tab, respectively, of said first metallic band so as to retain a formed shape of said first metallic band defining said pump casing; and a first impeller disposed within said first chamber; the pump being characterised in that further comprises: a second metallic band partially defining a second chamber of said pump; a third metallic band defining a third chamber of said pump with said third chamber being disposed between said first and second chambers and with a bent shape of said third chamber being retained through engagement of at least one tab and at least one opening (79a, 86a) at an interface between said third metallic band and said first or second plate (78, 79); and a second impeller disposed within said second chamber. a second metallic band partially defining a second chamber of said pump; a third metallic band defining a third chamber of said pump with said third chamber being disposed between said first and second chambers and with a bent shape of said third chamber being retained through engagement of at least one tab and at least one opening (79a, 86a) at an interface between said third metallic band and said first or second plate (78, 79); and a second impeller disposed within said second chamber.