Heavy scaling

i have a 20,000 gallon pool. 15x30 and 4-10 deep. The pool was abondoned for quite some time and there is a lot of scaling or calcium buildup. It’s everywhere in the pool and is sharp enough to cause scratches whenever my kids brush up agains the side and stairs to quickly. I tried a blue pumice stone and it last for about 10 brushes back and forth until there was only 1/4 left.

I did a little research and I think I need No Dran acid wash.

I have never owned a pool.