If any body wants to have tank water that is really hard to adjust, use municipal water from somewhere where they do lime softening. Picture dumping in huge amounts of calcium hydroxide to neutralize any free acids that may be present in the water. That means adding enough calcium hydroxide to increase the pH of the water to 10.3. This causes precipitation of calcium carbonate. Then you add even more lime to raise the pH to 11 which removes the hardness due to magnesium. Then to remove the carbonate hardness additional carbonate is added in the form of soda ash. This leaves us with water that will let soap lather but what a chemical mess. The final step is usually to pump a bunch of carbon dioxide into the water to lower the pH to a safe drinkable level. At least this water has had the phosphate precipitated out. Is it now more understandable why RO and RODI filters are recommended now. And this does even cover he potassium permanganate they add to oxidize the iron in the water or the polymers they add to aid in flocculation. Thats is forming particles large enough to filter things out. They floc together. That is a pun, really. Then there are the disinfectants such as chlorine and chloramines and many more under strange new names coming out constantly. And I go to school to learn to do this stuff. Whoopee, I can design water treatment and sewer treatment systems.