Test your fill water. It may already have a high pH or Total Alkalinity level.

This will definitely show up in your water test for the pool.

8.0 ppm is not really high, but I would suggest to continue to add acid as needed, and maintain the 7.2-7.6 ppm. Not maintaining either pH or Total Alkalinity, can result in a build of scale on the surface.

Be certain when adding muriatic acid, to dilute in a bucket with some of the pool water. Add small amounts around the pool perimeter. Pouring straight acid into the pool can damage the finish.

A weekly addition of a sequestering agent such as, Jack's Magic, will help in scale control

They have several options based on the sanitizer you are using.

Another consideration is an automated system that reads the water and adds the acid as needed, with the help of peristaltic pump. The acid is injected directly into the pool return line.

I found the alkalinity in my tap water is 300 ppm. I think I might have found the problem. Thanks. I wonder if there are inline filters that will help with that.

Check out APEC water systems. I have a system in my own home for water treatment and a water softener.

They have a great tech support and probably have something that will help.

https://www.freedrinkingwater.com/

Test your calcium hardness levels as well. High counts can influence pH and TA levels.