After the purchase, I immediately tested the option with water in the dust collector and a stocking on a HEPA filter. I collected quite a lot of garbage, but very fine dust still passed through the stocking and got into the HEPA filter. Had to use matches for cleaning. On the second attempt, I put a non-woven cloth on the HEPA filter (sold in rolls). I did not add water, but the result was better - all the fine dust was on the napkin, and only a trifle was shaken out of the HEPA filter. I'll experiment later to see which one is better.