What exactly are the test results of your tap water tests once it's been conditioned? In my opinion you are really over thinking and over complicating things here, which goes against your desire to have an easy to maintain tank. If you absolutely refuse to consider your tap water, then why not use a source of spring water, which still has all the minerals in it, like Deer Park? Deer Park has the minerals the fish needs and a neutral Ph, so you won't need to be adding all this other stuff to the tank. And you can get it anywhere.