Results of Ascorbic Acid Treatment for Stains

[Cookieman]

I have kept the ph low - 7.0 - 7.1 since trying the ascorbic acid treatment the second time. I did try the magic eraser on the steps one time when level got low enough. Some came off, but very difficult. I had an interesting conversation with a technician at JacksMagic. Filled her in on issue and gave her my numbers. When she heard calcium was only 90, she said Jack's products need calcium levels of 200-400 to work best as it gives it something for the metal to bind to. First I had heard of that. She believed that is why even double dosing did not sequester all the metal. I asked her about the sequestering test kit (JimK used one to determine if he had enough HEDP in his pool), but she did not try to sell it to me, but recommeded trying to raise calcium level first. Any thoughts? Any chorine now higher than 3.0 -3.5 makes the staining worse. Just been adding small amounts of AA to keep stains at bay temporarily until I can find out how to make the HEDP work. If the calcium addition sounds reasonable to the forum experts, where is best place to purchase it or brand (if it matters). Will calcium addition affect PH?