White Build-up on Tile Wall

[Lamar]

I have a gunite pool with a tile wall that extends above the water surface about 2.5 feet. The wall has two
shear descent type water falls in it. The pool uses a salt water chlorination system. The tile builds up a white material in a number of locations that is quite thick and difficult to remove. This material is heaviest after the pool has been covered for the winter and the water falls have not been used for months. The water is still cycled through the filters while the pool is covered in the winter.

Can anyone tell me what this material is and the easiest way to remove it. Your help is greatly appreciated.

[Guest]

scale

an acid scrub will remove it. keep your ph and alk within range to keep the buildup to a minimum.

what is the calcium hardness reading?

[Lamar]

Thanks for your helpful reply. I will check the calcium hardness.