Those sneaky Germans are always thinking of new ways to reduce noise. One way in which they have discovered a great noise reduction trick is by using silicone tubes in line with PVC piping. The silicone tube would come into play after the return pump. You can look at the above photo to get a better idea of where exactly the tube would be placed. Not only does this reduce noise, but it serves a far greater importance: if your return pump moves around in your sump (heaven forbid) your PVC pipes won’t break. By having the flexible silicone tubing inline with the return pipe it allows more give. Remember, there is a huge difference between vinyl tubing which isn’t as flexible and forgiving as silicone tubing, so if you want to give this trick a try be sure to buy silicone tubing.