What is the absolute quietest hang-on skimmer?

[mike31154]

Old schoold DIY counter current air diffuser skimmer. Only audible component is the air pump, so any sound produced is dependent on that single component. Small Aquaclear 301 power head in a pre-skimmer box provides water flow thru the skimmer and it's virtually silent since it's mostly submerged. On the other side of the coin, I ran an Aqua C Remora on a Mag 3 for about 8 months and that thing had to be the noisiest piece of equipment I've ever run on my system. I was actually glad when I cracked the intake tube during some maintenance and went back to the DIY unit.

Limewood air diffusers are still one of the best and most silent ways to produce very fine bubbles. Most of the newer technology skimmers use high power pumps with needle wheels and other relatively noisy technology to produce bubbles. It's difficult to design these components to be efficient and silent at the same time. A trade off in high performance I guess.