Hello I need some advice on how to remove concrete stains from my new vinyl liner, last year we have our pool renovated. We had stone coping installed around the pool with a new liner, after the work was completed I had noticed that some on the concrete that the coping was set in with has run off and left dried streak marks on the side of the pool I have scrubbed the streaks with pool bush the stain has not come out, wanted to get some advice on how to remove the stains,