Shane, I guess as long as you have a low TDS coming out of your RODI then no reason to change it. People do change it when it hits 1 though, I don't always, but I try to.

Ouch, the BFS kit comes with a handheld meter. You can get one of the dual inline meters that are always connected so you can monitor your filters effectiveness, but that's not included. The handheld is portable, the inline is not.