However, to be fair, unless there is something wildly wrong with it, not many people mess with these two values (some don't even care or pH).
Our bettas are tough little guys. My pH is up at 8.2 but my fish (including my goldies) are still holding strong. The key is consistency. If you start messing with it, then it turns ugly and complicated!
I've been recently under the impression (from both research and from member's problems, and life experience) that salt-based water softeners are somewhat bad for your fish....mainly due to the salt, not the softness of the water.
However it has been hard trying to find hard (no pun intended) facts about its truth.
I know my parents and family have had extreme difficulty keeping somewhat sensitive fish (tetras and the like) in their homes. The only person who has successfully kept fish alive was my aunt who does not own a water softener. Closely followed by me when I moved into this apartment (our water is ridiculously hard here).
I know wikipedia actually lists HUMAN health side effects from the consumption of the extra salt (for people on strict salt diets).
As for your test. Carbonate Hardness (KH) is actually alkalinity (but it is related to the hardness of your water). Is it measured in ppm? or dKH? I hope it's dKH :X
Hey, you just mentioned in a post that water softener can cause health problems for the fish? I have a water softener. :/ What will happen? I know that despite the water softener my carbonate hardness (KH) is super high, like 6 with the API liquid test.