I have a high CYA level of 200. I'm assuming these purple stains are are result from that?? Not sure, but I will be draining my pool soon and wanted to know if these stains can be removed with scrubbing the sides of the pool with a stainless steel pool brush or is there another method? Will these stains dissappear if I get the CYA levels down to 30-50 ?https://flic.kr/p/sa8gz3