Regarding "The very light dose of grow dots I used did not produce any salts on the surface," keep in mind that with water generally flowing through the soil from the bottom feeding to the top surface, salts are surely there in top layers, even if you don't see it. [How did you determine that bottom feeding "did not produce any salts on the surface?"].
Removing top layer soil and adding fresh top dressing (adding more nutes?) is a radical move, and I presume you will likely have to continue to remove top soil periodically. Doing this, the top layer is of no use for growing roots. I think occasional good drain-to-waste from the top is preferable. But check with actual AutoPot experts!