BALANCE is a USGS computer program for calculating mass transfer for geochemical reactions in ground water. BALANCE is designed to help define and quantify chemical reactions between ground water and minerals. Data required to run BALANCE are: (1) the chemical compositions of two water samples, generally assumed to represent points along a flow path, and (2) the chemical compositions of a set of minerals, organic substances, or gases, which we will call phases, selected as the reactants or products in the system. Implicit in this treatment is the assumption that only these selected phases participate in the chemical reactions that determine the composition of the final water.
This model is public domain and can be downloaded for FREE using the link below.
Updated geochemical software, integrated in a Window-based Graphical Interface, are available here.