I would not worry about any other stains - it was probably some kind of build up, and the magic eraser worked. If you really had a problem with metals, there would be more stains. All of your numbers look good, but I am not sure how you measure your TA. If it is just alkalinity, then it is a little high - Alkalinity should be between 80 & 120. But if your water is clear, I wouldn't worry about it.