Second, a more fundamental problem is the use of grids with extremely small number of points, far below the resolution required to describe the data. If, as illustrated in Fig. 3 , the predicted concentration profiles from these coarse models do not even qualitatively follow the experimental data, we question whether there are any meaningful conclusions that can be drawn from these results. Brookes et al. (2009) distract from this problem by incorrectly stating that such grids were the basis of the implementation of c(s, f r ) models in SEDFIT, which is well described in the literature to achieve excellent fits of the data to within their statistical noise. To the best of our knowledge the attempt to utilize coarse grids is without precedent prior to the Brookes et al. paper.