How to automatic mixing water

[golf nut]

I'm getting intrigued.

If I poured a gallon of ro/di water into a bucket containing 4 gallons of salt crystals then I anticipate that the solution would saturate then become stable, if I removed a known amount of that solution with a double acting cylinder and mixed it with ro/di in the correct proportions I should have a proper mix to be able to inject into the aquarium, if I then replace the saturated solution that I removed with more ro/di and at the same time remove the total mixed solution from the display tank and then repeated the process I should have a fairly accurate way of doing a water change , correct?