staining of stairs

OK I am past frustrated with the staining of my pool stairs. I started in April balancing the water of my 25000 gallon vinyl inground pool. I followed the ascorbic acid treatment exactly. And my pool looked great. No staining! After 2 weeks I began shocking the pool to raise chlorine levels and stains came back slowly. I had water tested and it showed no metals. Chlorine was still low so I repeated process and stains dissappeared only to reappear several weeks later. I have spent a small fortune on metal remover and stain remover which work but not for long. Could there be some sort of metal in the shock I am using? Besides the light brown stairs my pool looks beautiful. Water is blue and clear! Thanks for any help.

Metal remover doesn't actually remove the metals--the only way to remove them is to make them drop out of suspension (which is what's happening to your steps) and filter them out. The other option is a metal sequestrant, which keeps the metals in suspension so that they're still technically there, but not visible. Pooldoc or Mbar are the ones to advise you better on this, but just know that once you have metals in the water, they're going to be there, unless you filter them out. MIght want to take a look through the "metals" forum, there are lots of threads from others that have metals and outline what they've done to deal with them.

Janet