Filtering should, at minimum, remove redundant (identical or nearly identical configurations) and energetically high-lying configurations, as well as obviously unphysical structures (e.g., clusters that have fragmented or undergone unwanted reactions). Caution is advised when applying energetic filtering using specific cut-off values. For instance, low-level QC methods may predict the relative energies incorrectly, and a good filtering algorithm should take this into account. Therefore, the choice of appropriate filtering criteria is as important as the choice of methods at different levels of the bottom-up approach.