DIY Automated salt water mixing system

[Seth81]

So I had this idea for making salt water automatically. I already have a system to make RO/DI water, store it, top off as necessary, and also to manually mix SW water to use for water changes. But what I've been lacking is an automated way to replenish the salt water.
So my idea is this; Add a third tank for saturated saltwater (SSW), so basically dump two buckets of salt into the SSW tank and top off with RO/DI water. The salt should be able to fully dissolve to create water at a SG of about 1.185 (approx 7x that of normal SW) in the SSG tank. Alternatively I could put in 4 buckets of salt and top off with RO/DI which would result in un dissolved salt on the bottom of the tank, and saturated salt water above, and then the saturated water can be replenished one further time with RO/DI water before more salt is needed.
To fill the SW tank I could fill the SW tank in a 1:7 ratio of SSW water to RO/DI water, or perhaps use a conductivity probe to control the amount of SSW that goes into the SW tank. A second pump would be added in the SSW tank to simply circulate and mix the solution, and perhaps a heater to aid in dissolving the salts.... however water at 100 degree C can only contain 28% salt, compared to 26% salt at 0 degree C, so not too much of a gain.
I guess one question I would have to any chemist types, is would Calcium, magnesium salts dissolve as readily as Na salts. If not then I probably shouldn't use the 4 buckets of salt approach, could only stick with the 2 bucket approach.

Any thoughts or comments