Half a cup of dry pickle for a good size crock pot will work. Remember to pour water first, than to add pickle. When water evaporates ad more water (but not pickle). If you solder silver only, your pickle may last literally for years. If you solder copper or brass you will have to change your pickle when it goes blue. To change pickle add baking soda 1 table spoon at a time. Wait for your pickle to stop reacting (“boiling”) after each spoon before you add the next one. Pickle is neutralized when it does not react anymore.