Dosing vs. quality salt

[troni]

So I was given a suggestion that made half sense. I was told that instead of dosing if you do religious water changes with a quality salt it will keep your levels at par. Now i dont see this because your adding water with proper levels to a water with low levels, overall youll have a level inbetween which is still below ideal.
Now i understand the use of quality salts. My Q is am i missing something? Does anyone do this with great growth on your sps?