July 15 update - on July 10 I started added small doses of liquid bleach to the pool. I later added a trichlor tab to the skimmer as per PoolDoc's suggestion. I forgot to remove the culator bag from that skimmer, so that pack is now destroyed. I still have the other one in the other skimmer. Chlorine levels are now up to 5 ppm, but I am sad to report that the stains have returned, though not as bad as when all this started. I give up - will live with the light yellowish tinge on the pool walls, and if I make plans for a big party or anything like that, I will do the ascorbic treatment again.

I had been running the filter 24/7 while doing the ascorbic treatment (which lasted one month). I also vacuumed the pool twice a week, and then backwashed after vacuuming. Have not filled pool in the past month since we've been getting a lot of rain. Should I have drained part of the pool after the metals had been sequestered rather than waiting for the culator packs to pick up the metals?