I am planning to purchase a softener, and have been reading the various information regarding sizing, which seems to be more geared more toward ensuring one doesn't get a softener that is too small. But why not purposefully get one that is too big? It seems that everything I read indicates that it takes less salt to run a larger unit at lower capacity, but maybe I'm missing something.

I have a house with 2.5 bathrooms, and I may add 1.5 additional bathrooms. I also plan to add a large shower (maybe 2) with multiple body sprays, etc. There are only two people in the house, and the water district report shows an average of 11 grains of hardness per gallon, with a range of 3-16. I have a 1" copper loop in the garage where it could be installed.

I'm considering a Fleck 7000 system, and thought a 1.5 cubic foot / 48,000 grain system would be plenty; but why not just get a 2.0 cubic foot / 64,000 grain system? Is there a disadvantage? It doesn't really cost much more, and the additional space is negligible.