That makes sense. I guess I could have them check my fill water, but I know it's metallic b/c the Vit C test. Anyway, I guess I will try and clear up the water (which now looks like a pond) first and then address my stains. Could the pool store lady be right? - change my sand every 2-3 years?. It just seems like the sand would continue to filter if you keep it backwashed.
Thanks again to the forum.