In my experience they are, mine that i have at the moment is as quiet as anything. Strange, i guess it varies depending on situation.
Well I have had 3 of the smallest pumps [background=rgb(247, 247, 247)]
Eheim make, they all made more noise than my cheapo £8 air pump from China. [/background]
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The reason I bought the Eheim's was because they were supposed to be quiet but I was quite disappointed. [/background]
[background=rgb(247, 247, 247)]I guess you got lucky with a nice quiet one.[/background]