Systems, apparatus, and methods for sensing species in fluids. In accordance with some embodiments, methods comprise activities such as diverting of the fluid into an analytics spool. These methods also comprise causing the fluid to separate into layers. Furthermore, they comprise sensing the type of fluid flowing at a position where water is likely to flow. Some methods further comprise sensing a pressure, a temperature, and a total dissolved solids concentration in the fluid. Moreover, such methods can comprise comparing those conditions to precipitation curves for a plurality of species. These methods can also comprise determining whether a particular species might be precipitating from the fluid. Some methods comprise sensing a carbon dioxide and an oxygen concentration in the fluid. Moreover, such methods can comprise determining whether a ratio between the carbon dioxide and oxygen concentrations has changed. Additionally, or alternatively, such methods can comprise sensing a hydrogen sulfide concentration.