Off topic a bit, but a batch of Centennial Blonde was exactly what prompted me to look at water chemistry as well. My CB came out very grainy, a bit astringent, and just didn't taste good. I knew it had to be my process because a million homebrewers have given that recipe rave reviews.
Heh. I tasted mine, thought something was wrong and handed it to SWMBO for a second opinion. She tasted it, made a yuck face and said "Ooohhh! Blech! ... I mean uh, that's GREAT, honey" with a wink and a playfully sarcastic thumbs up.