phases. Based on Fig. , the evolution of the structural parameters describing different aspects of the medium are closely correlated with the progress of struvite growth. In particular, I 1 reflects the electron density weighted contribution of OZ fluctuations to scattering. As we move from a 0.1 M DAP solution at 0 s to a 0.05 M struvite "solution" at 10 s, there is a ~30% increase in I 1 (Fig. ), indicating an increase in the "concentration" of OZ fluctuations, which we interpret as a liquid-liquid separation event preceding struvite nucleation. After 10 s, the value decreases gradually over a period of ~60 s, eventually reaching a level that is ~30% lower than the initial value characteristic of 0.1 M DAP. At this point, a plateau is reached, likely corresponding to a characteristic feature of a fully equilibrated solution. Although the contribution of OZ fluctuations decreases (i.e. their "concentration" as measured by I 1 ), the extent of the heterogeneities expressed as ξ OZ (Eq.