Abstract: An automatic fluid mixing system is disclosed which, in its preferred embodiment, discontinuously opens a disposable multi-compartmented module to permit the mixing of initially released contents before the subsequent opening of remaining compartments, flushes each compartment with base liquid, and utilizes knife-edge pairs to slit the module in a manner which permits rapid release of the contents.The preferred system additionally includes means responsive to specific gravity of the solution for controlling the amount of base liquid introduced into the solution and a level sensing mechanism including a magnetic float assembly employing magnetically responsive switches to electronically sense liquid level.