Just wanted to add to the thread, one of the reasons that you probably got the stains in the first place is that when you added the ph+ your chlorine may have been high. High ph + high chlorine will make any metal that is in the water fall out onto the pool surface. I don't know why your pool manufacturer would not endorse a sequesterer, but will endorse metal magic or Jack's Magic - the Jack's Magic pink stuff is a sequesterer! In any case, check your trichlor tabs to see if they have copper in them - some of the trichlor is adding copper as an agelcide right into the tablets. Fiberglass pools are very suseptable to staining. I run my pool at a ph of no higher than 7.4, and keep the chlorine at the low end of the "best guess" chart. I also keep a sequesterer in the water at all times. One way to handle stains that pop out is to take the ph down to 7.0 - 7.2 and add a sequesterer - this will sometimes lift a stain that is new. If the stain gets more embedded, then a treatment with ascorbic acid (vitamin c) will take them off. I hope you got your pool closed for the winter, and next year when you open I can help you keep your pool stain free I can't waint till the next swim season