Hi all, I have deposits on the side walls of my liner. They do not come off with regular brushing, I can get them off with very aggressive scraping with my fingernail. I've had them a few years not sure what from. I believe the algae problem I have is due to these deposits being an easy spot for the algae to start. No matter what my chlorine level is the algae will accumulate on the sides. Question is, can I get them off? Will I tear the liner up doing so? Should I buy another liner. The pool is between 8-10 years old. Thanks in advance