Did you calibrate the pH pen you used? I don't have a digital pen, but I know that many of them have to be calibrated using a solution with a neutral pH of 7. If it hadn't been calibrated, that's probably the reason you got such a high reading on both. If you're unable to get the calibration fluid right away, maybe think about picking up an aquarium liquid test kit, and using that on your tap water. If you're still getting a reading in the 12s, you'll definitely want to stick with the distilled water/CalMag. 12.2 is really high, so double check to make sure it's not your pH pen that's off the mark.

Edit: 6.6-6.8 is pretty ideal pH conditions for soil based mediums.