As Fig. 6, but now showing three sets of models. The dotted lines show the ¹³ CO (top) and C¹⁸O (bottom) J = 3−2 line fluxes for models with standard DALI chemistry, that is, without CO conversion. The solid lines show line fluxes for the models where CO has been chemically converted into other species, as described in Sect. 2.3.2. The dashed lines show line fluxes for models with maximal CO conversion, where we have removed all CO in the region where CO conversion through grain-surface chemistry occurs (see also Sect. 8). Observations in Lupus are shown in orange if detected and gray if an upper limit (Ansdell et al. 2016; Yen et al. 2018). Stacked non-detections are shown in black (see Sect. 3.3).