Slamming /hard crusty sand like debris stuck to vinyl

Been a while. Not new here, but last year was my first year with a pool again and I didn’t do a good job due to my health. It sat through winter all nasty. We had yard work done so we drained and took it down. The inside is still filthy. We set it back up and I’m in process of slamming it but there are hard sand like pieces stuck to vinyl. What are these and is there something safe to use to help get them off. I have neck issues and having spinal fusion soon so I can’t scrub as hard as I would need.

I’m also needing new test kit but trying to slam done before Memorial Day and won’t get kit in time. Can I wing it with a 3 way test kit? Vacuuming is killing me but hubby left wrinkles again and I’m not sure a vacuum can make it over it