I am currently helping a friend that has let their pool get away from them. Over this last weeked, they drained and refilled their 25K gallon pool. I have been able to help and advise them about the water and it is now under control. The bottom of the pool is very stained - looks dirty. Does anyone have any suggestions other than a complete drain and acid washing? I realize that acid washing is probably better left up to the pros, but we're pretty hands on people that wouldn't mind tackling this.