I'm with Butcher and Geo, there is something in the water that makes his work for you. As far as I know deionized water is a very good insulator and shouldn't be able to conduct any current at all. Are you using tap water?
If you are watching the silver come off in flakes then you aren't dissolving the silver, you are attacking the metal below and the silver plating is dropping off.
What happens if you use a pure silver object? If your solution is attacking the silver in silver plate then it should do it with a massive silver object too.
Anyhow, an interesting way to do things, maybe something usable will come out of this. Keep us posted.
Btw Butcher, colloidals doesn't have to be metals, a good (pun intended) counter example is colloidal fat in milk. :-D
/Göran