If not filtered out after each cycle, visible particles definitely settle to the bottom of a US tank, aggregating into long chains of grey fluff. Some remain at the bottom, and some agitate into the middle and upper reaches of the tank during use, settling to the bottom thereafter. IME, if using a standard open-bath US tank that is periodically filtered, it’s best to draw those heavier aggregated particles off at the bottom. However, as the Degritter filters during the cavitation cycle, the opposite direction of flow may make sense. At that point the unaggregated particles are small, widely distributed throughout the tank, and will likely follow whatever flow of current is presented.
I didn't read the entire website, but it would be good to know how fine the filter is. Mine catches 1um particles. At some point I'll probably shift to a .5um filter.