My aquapure a couple of months ago or so said low salt so I put in a couple of bags of salt. It then read high salt for a little bit and then gradually dropped down and I assumed the problem was solved. 2 days later it was reading 1.8 which I knew wasn't right so I took the sensor out and the metal things were covered with whitish like grime. I cleaned them up and things have been fine until a week ago when it happened again. I cleaned the same grime off and now it just happened again and I again cleaned the grime off it. Is there something I can do to stop the sensor from getting coated with whatever whitish stuff is getting on it?