my tests of my water before water change are . am 0, ni 0, nitrates about 15, ph betwween 7.6-7.8. been that way for 8 weeks now when i do a kh test it comes out about 35. my question is since all my tests are good and my ph staying constent sould i be concerned about kh my water hardness. now my local water company says our water is on the soft side.

Yes, you need to raise your kh. Kh is what keeps your ph steady, if your kh gets too low your ph could crash. You can put some (rinsed) crushed coral or crushed oystershell in your filter to buffer your kh. Try to get it up to 80 ppm minimum, up around 120 is better. Good luck!

Yes, and goldfish need water harder then 35. The natural habitat is usually hard water. I'm not sure, but adding salt might raise the hardness. You might check with your trusted pet store or do some internet/koko searches.

-Ed