Get a product called IRON OUT. Look it up online and read the directions . I'm assuming you are dealing with a lot of rust. . It smells terrible on contact so put it in and Go away. Come back later. You'll be amazed. Also works great in back of toilet tankHope this helps.

I have no issues with rust, the salt tank is made out of plastic. I'm assuming the salt contains some inpurities that surface after the salt gets dissolved. It's mostly dirty water that's bothering me. What I would like to do is get all the salt and the water out, clean the tank, and put everything back in. Only I don't really see how to do that since the tank contains at least 100kg of salt + about 200l of water.

In our old house we had a water softener that consisted of 2 pieces, one big plastic container where we poured the salt and another that looked like a large oxygen tank. Every couple of years I would empty out (bucket by bucket) and disconnect the tank (never fill it with salt to the top) and then haul it up the stairs and out to the drive way. There would be a block of salt that had melted a formed a block on the bottom of the tank (and I used salt pellets). Then I would carefully use a shovel to help break up that block. then hauled it back downstairs, rehooked everything up and we were good to go for a couple more years!

My mother's softener had a smell to it and I asked at the local softener/salt place what to do about it. They said to pour a cup of bleach into the salt. That worked for her. But you should ask around about it and not take my amateur advice.

Hm, thanks for the bleach advice, it might work. I'll check around to see it it could be a solution.

I've looked online some more and it looks like my only option would be to dissolve all the salt and just use a vaccum to get all the water out. Would be great if I could take it outside but unfortunately the oxygen tank thing is part of my salt tank :(