Despite the relatively slow injection, mixing and pumping times, the 10 s resolution was sufficient to capture several snapshots of the early-stage struvite evolution before reaching equilibration at ~60 s (Fig. ). Below, we describe the observable features in the patterns, based on which we formulate a model to quantify them. In the next steps, we interpret the evolution of struvite based on the identified scattering features and the as-derived fitting parameter values. In all the curves shown in Fig. , two broad maxima are observed at ~20 nm -1 and ~29 nm -1 , characteristic for water (or diluted aqueous solutions in our case) . The main peak at ~20 nm -1 originates from the O-O average spacing of ~3.1 Å. The second peak at ~29 nm -1 , often classified as a shoulder of the first peak, represents the tetrahedral structure in the water network. Moreover, from the perspective of the aqueous medium, there is a plateau in intensity (I(q) ∝ q 0 ) for the range of 0.5 < q < ~2 nm -1 , whose position normally corresponds to the isotropic compressibility of water . It is also proportional to the square of the scattering length density contrast of the aqueous medium. In the intermediate range 4