Based on your KH, the titration kit is giving the result I would expect for your aged water. I wonder if one or both of your calibration solutions are the real culprit for your strange results? Could either of them have been accidently contaminated?
Either way your plants and fish look really heathy, and I would definately trust what they're telling you over a test kit.
Either way your plants and fish look really heathy, and I would definately trust what they're telling you over a test kit.