The wife insists on using potassium chloride instead of sodium chloride. She claims that the sodium chloride corrodes the fixtures and leaves a residue. We haven't used salt in 20 years and I challenge her recollection as flawed. She was sold on the health benefits of potassium versus salt back then but when she switched, didn't like the taste it imparted so I bought a distiller for the drinking and cooking water. This got to be a real PITA so I installed a RO filter instead. She even uses the RO water for the house plants.
All of the local dealers are sold out of potassium and say there is a supply chain problem pushing up the price. The best price I paid was $10 for a 40 lb bag but recently they had been demanding $15 before they ran out. The last bag cost me $25 and I had to cross the border to get it. This is just insane. I can buy sodium chloride for a fifth of that price.
My softener uses a manual clock with cams and as such I cannot adjust the timing of the various stages. All I can control is the frequency of regens and the flow rate of the brine fill. Unless I am using way too much salt and the preset rinse stage is too short, I cannot see how it can be corrosive to the fixtures. My high school chemistry is a little weak, but it seems to me that it is the chloride that is corrosive and that part should be going down the drain in the rinse stage.
Given that she uses RO water, I don't see much of any benefit to using potassium. I doubt there is any validity to her claim on it being less corrosive and leaving less residue. The potassium chloride that goes to the drain actually goes to my sump pit rather than to the septic tank and the trees downstream of the sump discharge show signs of stress from it so I challenge the claim of less environmental impact. I doubt switching to salt would make much difference to the trees.