Because I used "froggy" for a brief period of time, I have a "pool ring" at the water line from the copper algaecide and the silver in the froggy. I do not have any other discoloring in the pool, just at the water line. I know that ascorbic acid gets metal stains out, and I know that citrus is high in ascorbic acid. So can I use orange or lemon juice (pulp free) to get this ring off, or should I just get some ascorbic acid?