You don't worry about it. This type of setup typically isn't meant for filling a container and then completely emptying it. It's meant to have salt water and fresh water on hand at all times.
That's what I figured, but wanted to hear from someone more experienced. Should I worry much about precipitation (alk/Ca drop) when salt water sits in the tank for days? I use Rea Sea Pro salt. Thank you for taking time to answer my questions...it's really appreciated.

