The end of March I had someone come out to see why my fiberglass spa was stained black. The tech had never seen that in his 9 years and thought it was algae but I told him it was a stain and we felt the surface and it was perfectly smooth. So he took a picture and called his supervisor who told me that it was ruined but they had great prices on NEW ones !!!! So the following week I googled it and found a chemical treatment that removed ALL of the stains in one day. I emailed AZ spa tech with before & after pictures and the owner replied that he wished he had seen the before picture (???) and he would love to know how I fixed it. I emailed back that I would let them know the details if they refunded my $90 service fee. It's been THREE weeks and I've heard nothing back !!!