Hi SMC;

The only problem with your "Ascorbic Acid" (vitamin C) is that it's "Citric Acid" (lemon juice acid)!

You can use citric acid for metal clean up; some pool chemical companies sell it for that purpose. But, it's not as effective as ascorbic acid. However, with the larger dose it may well work very well for you. Keep in mind that neither citric or ascorbic acid are chlorine compatible -- chlorine rapidly destroys both. Also, the by-products formed when chlorine breaks down citric acid are better not breathed -- so don't swim once you begin re-chlorinating, till you've held a chlorine residual for a few hours.

And . . . if you'll use polyquat while your are using the citric, you won't have to worry about the pool getting algae. Polyquat is compatible with BOTH chlorine and citric acid, so you can begin adding it while you are letting your chlorine levels drop.