I don't use an aluminum pot to clean silver.I presently use an electrolysis set -up; but prior to the electrolysis set-up I used the "aluminum foil in glass container" method in which I placed a portion of aluminum foil in a shallow glass dish, added a couple of tablespoons of sodium bicarbonate placed on top the aluminum foil, then placed the coin or ring in the the bicarbonate, and then pour boiling water over the bicarbonate....let it bubble until it bubbles no more...remove the item and rinse in cool water....repeat this process for as many times as necessary using fresh foil and fresh bicarbonate soda.
I hope this helps you
p.s. I did read on the forum that someone uses the aluminum pot method successfully , but I'm not sure of the exact directions on that method...maybe someone can post it again for you.