"Moka" grind is imperative. Most guidelines that I have seen recommend somewhere coarser than espresso and finer than drip (e.g., illy, Blue Bottle, and a bunch of blogs when searching "best grind for moka" or so). Finer and you might overextract and result in a bitter brew; too-coarse and the machine won't extract properly or develop any pressure in the bottom chamber.
"Moka" grind is imperative. Most guidelines that I have seen recommend somewhere coarser than espresso and finer than drip (e.g., illy, Blue Bottle, and a bunch of blogs when searching "best grind for moka" or so). Finer and you might overextract and result in a bitter brew; too-coarse and the machine won't extract properly or develop any pressure in the bottom chamber.