Have yellow staining on vinyl...never had before. I have 24 ft round x 52" tall vinyl above ground pool with 16400 gal. Had water tested today using pool watch water analysis with the following results:
total chlorine 6.0
free chlorine 5.9
total alkalinity 71
calcium hardness 29
Added 4 ounces Algecide and 5 pounds alkanality high. How do I remove the staining and what's causing it.