I use these that are designed for septic tanks. Not the cheapest but the diaphragms have lasted me for 3 years of almost 24/7 use and are easy to replace if need be. Of the five I have owned at least three years, I just replaced one diaphragm recently for the first time because the flow dropped a little. They have them available with an audible alarm if the pump fails for whatever reason. Lots of sizes available.

I use the ET60 size for my 150 gallon fish tanks and mbbr barrel for up to 4 cubic feet of media. 60 lpm but supposed to use only 40 watts of electricity. Haven't checked with meter.

Extremely quiet! I've also used them outside with no issues. Beware of cheap pumps! Got a cheap one once that didn't put out the air as advertised. Not even close.

Even though they are located inTennessee, the two guys that run it are from England and definitely sound like it!

http://www.bluewaterpumps.com/air-pumps.php

Last edited by Cecil Baird1; 12/09/15 07:32 PM.
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.