this is my first time to this forum and I would very much appreciate any feedback.

The pool store today told me I should use "Stop Yellow" to get rid of the film I am seeing on top of my water. He told me to shock the pool and then add it. I have a SWG so I assume I can just super chlorinate, but do I wait until the 24 hours is over? Can I be swimming while this shocking is going on? I think I am in way over my head.
Thanks