Something white and crusty stuck to AG liner

[Hightech]

I have no idea what it is, maybe some type of calcium, all I know is it WILL NOT come off by scrubbing, so im looking for some advice if anyone has any, I found it after taking the winter cover off this week. This is a 30' round if that matter. Im not the kind of person that puts to many chemicals in my pool, this pool is going on 5 yrs old and mostly ive done nothing but put chlorine in it over that time frame, other than the polyquat recommended before closing, but thats about it

[aylad]

Sounds like calcium scaling...can you test for and post results for CH, TA, and pH?

Janet