MAybe a reverse osmosis unit, which forces water thru fine filters. Though this may be cost prohibitive for an individual home.
Can you re-pipe the drain line in such a way that the whole pipe could just be swapped out every few years ? Maybe you buy a few lengths of pipe, some elbows, pipe thread sealant, and keep them on hand ? Or find a roll of Hose / tubing of the right size, clamp it in place between the unit and the floor drain[?] , and swap that out every other year. Plus if you get see-thru tubing, you'll have an idea of the progress of the buildup.
Short of mechanical scrubbing to remove the deposits, i'm not sure how you would even use chemicals to break down the salt restriction that only affects the drain line [?]