Good Air Pump

UPDATE: 

I found this air pump that seems to be exactly what most of us would want.
The AP 100 is quiet at 45db.
It pumps 144 liters per minute at zero head pressure
And the pressure is outstanding - 181 inches of water, but they conservatively claim 11 feet! 
100 Watts is not bad either.
It even comes with a rebuild kit!
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This General Hydroponics air pump is Extremely Quiet has a lot of pressure (84" of water) which is required for many air lift situations. 20 liters per minute is not earth shaking but it's enough to air lift the water for my Earthan Beds. 

The quiet operation and psi of this little $69.00 pump really impress me.  General Hydroponics does not state in db how much noise is made, but I think it could be placed next to a living room aquarium.  The sound of the bubbles would probably be louder than the pump.

http://www.1000bulbs.com/product/95293/GROW-GH2716.html?utm_source=SmartFeedGoogleBase&utm_medium=Shopping&utm_term=GROW-GH2716&utm_content=Air+Pumps&utm_campaign=SmartFeedGoogleBaseShopping&gclid=CN7G2qO-8rsCFcVQ7AodEVIALw

General Hydroponics GH2716 - Dual Diaphragm Air Pump

www.1000bulbs.com

Shop for General hydroponics GH2716 Dual Diaphragm air pumps. Four outlets pumping 20 liters per minute. Low prices on air pumps at 1000Bulbs.com.

Another good air pump is the Hakko.  Here are the specs of the six modles they build.
Hakko25 - 21 liters per minute, 17w, 3.7 psi (32dB)
Hakko40 - 51 liters per minute, 40w, 5.5 psi (35dB)
Hakko60 - 68 liters per minute, 63w 6.7 psi (38dB)
Hakko80 - 86 liters per minute, 85w, 7.8 psi (38 dB)
Hakko100 - 105 liters per minute,116w, 6.5 psi (40dB)
Hakko120 - 121 liters per minute,126w, 7.8 psi (42dB

For large air I have used the Active Aqua 70 lpm and the Eco-Plus 7 with 200 lpm.  Both of these are very loud.  My Active Aqua 70 lpm destroyed itself in less than a year.  The Eco-Plus 7 has been in continuous use for about a year and it runs much cooler due to the larger fin size.  Eco-Plus 7 is the better pump in my opinion.   Mine uses 60 to 90 Watts even though it's rated at 200W.  It also will pump to a depth of 84".

I have no experience with the Elemental O2 Commercial Air Pumps but the
571 gph/43 lpm delivers 2.47psi
951 gph/72 lpm delivers 3.48 psi from 41watts
1157 gph/87.6 lpm delivers 4.64psi


1 pound per square inch = 27.6704523 inches of water.