It was not a bearing it was the cover plate or volute, it was from a 50Hz pump and the wrong dimensions internally and this allowed the impeller to rub on it. We replaced all of them except 2 and unless you bought it used from someone in Texas as those 2 were raffled by the local reef club and I have not been able to track them down, yours will have the new piece. The pump is not dead silent and never will be, it is a large pump and it should be quieter than any air cooled pump but it will never equal the noise level of a much smaller pump like an Eheim. I would give it a bit of time, they do tend to be noisier at first, the impeller is huge, it literally runs almost the entire length of that block and as a result some air is always trapped inside when they are new, it takes about a week in my experience to get all the air out. I think your plumbing is OK but rigid plumbing always conducts more vibration. The best solution is to place a rubber pad under the pump and then use the screw tabs on the pump base to fasten it down so it cannot vibrate and reverberate off the plumbing. The only other thing I can say is I have gotten pumps back for noise that had gotten debris like gravel inside of them and this will definitely make noise but it is a screeching noise and not vibration. You have to be very careful opening the pump as the shaft is ceramic, it is about the diameter of a pencil and you couldn't break it in your bare hands but with the leverage of removing the volute, if you pull it to one side it will break, it has to be pulled gently with a straight back motion.
