20 mesh is too big for the blue bowl. Run 30, 50, 100 etc. for the finer gold. Drop the water level 1/4 " for each mesh. 30 mesh water is at the top of the bowl. 50 mesh drop water level (speed) 1/4" from the top. 100 mesh 1/2 " from the top etc. 30 mesh can be fed 1 cup of material at a time. All others 1 tablespoon at a time. When you are ready to remove the gold use a turkey baster to blow the gold and any other fines left to the outside edge. Then restart the bowl at the proper speed to clean the remaining light material out to leave only gold in the bowl. Then use a suffer bottle to remove the gold and put into a vial. Do this for each mesh size.
Good Luck !!
BH Prospector