Calcium can precipitate out to a hard surface what are you talking about? It can cause ball valves to stick, it can stick to glass, foul check valves, etc.
When you scrape the 'white dots', they are hard to get off but once you get them off, they disappear or dissolve back into the water column normally, or that's the way the formations I clean off always react.
I think you need to do some more reading before you can say calcium can't precipitate and form hard calcerous formations because its happened to plenty of people on here and has been discussed plenty of times.