Very little noise and does exactly as advertised. Currently working 2 large sponge filters with great results.
The pump is pretty good, I got the AP-100 and have it connected to a sponge filter and 2 air stone and it pushes lots of air, even when set to minimum. It is somewhat noisy but I'm getting used to it. Overall, I think this is a good pump for larger tanks.
Really quite at first but still quite but if I choose to listen for it/to it than I can hear it well. The sound it an even sound so it's more like white noise at this point.
This is comparable to the whisper tetra air pumps, I used this to transport fish and is extremely quiet and reliable.
A little loud but so far is working.