I try to keep my sacrificial anode as clean as possible but the rust seems to embed itself into the stainless and can be difficult to clean, I have been experimenting with different methods of cleaning the piece of stainless and have been cleaning it with a 5% solution of Muriatic acid and water, I place the anode in a tank with the solution and the anode cleans up very nicely after which I rinse, wash with soapy water and rinse again. This seems to work out well with little elbow grease needed.
Anyone else have any methods of cleaning their anode.