check this out. Its simple. And affordable.
Once a year change the filter.
http://www.freshwatersystems.com/blogs/blog/what-are-water-heater-filters-and-how-do-they-work
hard water kills water heaters every 10 - 12 years max.
So they can be of help. My mother in laws water heater lasted over 24 years and was still working great when she passed. It was a Rheem..
Just something to possibly take a peek at before ya get all set up...