SALT-X may work but as tue says if you use the engine regularly you only need to flush it out with neat water.
If you leave it for long periods and to break up the salts you flush it with vinegar (a chemist told me this). Vinegar for some reason reacts with salt and desolves any salt deposits pretty quick. I put in a bucket water, vinegar and also JUST a drop of fairy liquid works wonders and keeps the impeller in shape too work the engine for a few minutes, then flush it again with fresh water and that's it. I used this method for a long time now, I have a 2-stroke Johnson 9.9 since 1977 and still runs with no problems.
SALT-X may work also but why should I pay for something is not necessary to use?