Your well water depends on the kind of terrain it has percolated through.It's smart to test its hardness ("GH") its alkalinity ("KH" or "carbonate hardness") and its pH (after it's stood in a glass overnight).
If it's softened with a "salt" brine, you could start changing over from sodium chloride to potassium chloride (KCl), without harming your system. Confer with your water softener dealer. It's a little more expensive, but the potassium ion it puts into the water is less harmful than the sodium ion from regular "salt.". It means you can pour wastewater onto plants in the yard, for one thing. And if you have plants in the aquarium, they'll use the potassium and it won't build up so fast in the water.