I tried several pumps, almost no was really quiet, and the Tetra etc., which are often recommended. This on the other hand here is much calmer, in a closed cabinet you can not hear them, as the outlets of the bubbles are clearly disturbing. And even these are slightly better than the Blubbersteine that you usually get to - but it must be said that the adjustable Blasenauslässe prevail in the aquarium naturally quite fast. In addition, the engine was subjectively louder, you hear him now and then quite easily now, often it helps to reposition the pump a little, then the sound is gone.
