white calcium line

[waterbear]

muriatic acid will remove it.
It's calcium scale and basically a water balance issue. Many parts of Arizona have very hard water (as we do here in parts of Florida). You can minimize it by adjusting your water balance. It's pretty hard to do much abut the calcium hardness but it is possible to lower the total alkalinity if it is high enough to be contributing to the scaling and in most cases it is fairly easy to keep tabs on the pH to help minimize scaling conditions.
High pH is the main factor that will contribute to scaling conditions that is easily adjusted but it is something you need to keep on top off all the time.
However, please post a full set of test results so we can see where you are now and what changes you could make that might help prevent scale from forming as fast.

[Phillbo]

Mine does not get much build up but once a year I hit it with a pumas stone and it's fine.