+ The most common cause I've seen for a rough liner is what I've called "sand algae". Under certain conditions, some forms of algae and slime will either secrete tiny calcium domes that adhere to the pool surfaces. You can see some extreme examples here: http://pool9.net/algae-sand/

+ Do NOT rub a trichlor puck on your liner; they are VERY acidic, and low pH will do serious damage to a liner. If you have stains that respond to high chlorine, dose your pool with bleach at night, and let the stains gradually disappear.