i second Fat Boys response. don't mess with that pH buffer stuff, especially if you are blessed with neutral pH straight out of the tap. makes no sense. just lose that pH junk, it'll go back to 7 after a bunch of water changes over time.
even those of us without neutral pH don't mess with our pH. my pH out of the tap is about 8.5, but i'd rather keep it stable and just work with it then play around with chemicals that could possibly wreak havoc with water stability.