My sand has always been clean after it so i just put straight into the tank, i know what your saying but, surely the fabric should act as a filter and keep it beside the sand, this is what i was recommended to do on another forum (think it was plecofanatics if not it was a betta forum) and for whatever reason it works for me, i found a couple of twiggy things when i was scooping the sand out the case with a small pot but it certainly took all the smallest particles out that cause the clouding and there couldnt have been more than 3 of the twiggy things, i used builders sand and poured boiling water over it first as some of the people recommended it to ensure its sterile and there was nothing living in it, been using it in 3 tanks since i moved house about 6 month ago with no probs and got clear water in all the tanks in a few hours.