@TerrorIncognita @DavidElfstrom @ariccio Box fan on speed 1 or 2 is not particularly loud and may still perform better than a small commercial air cleaner. For a one-filter build maybe consider 20x20x4.
@TerrorIncognita@DavidElfstrom@Aricio Box风扇在速度1或2上的声音不是特别大，可能仍比小型商用空气滤清器性能更好。对于一个过滤器构建可能考虑20x20x4。