What the heck is the "vibrator pump" method? I'd say your concept of how an
AC motor works is a bit weird. There is really nothing inherently more
efficient about a magnetically coupled, sealed, pump over what you are
calling an external pump. Every power head I've ever seen uses a sealed
rotating magnetic field which couples to a magnet attached to the impeller
shaft. What you are calling an external motor works in almost the same way,
a rotating magnetic field couples magnetically to a rotating shaft which is
then coupled mechanically to an impeller. The only advantage I see in a pump
mounted external to the sump is that it won't transfer heat to the tank.

Tankdoc

----- Original Message -----
From: "Wayne Sallee"
Newsgroups: rec.aquaria.marine.reefs


Pszemol wrote on 10/31/2006 3:46 PM:
Powerheads like quiet one 3000 give you more water
movement per watt of electricity than external pumps.

Yes, that's correct. Because of their design, they will use less
electricity. External motors don't use the vibrator pump method, but are
actual motors that continue to move the shaft in the same direction until
it gets into the next position, and then the next electrical contact is
made, forcing it into the next position, and so on, and so they use more
electricity.

Wayne Sallee
Wayne's Pets

"Wayne Sallee" wrote in message
.net...
Pszemol wrote on 10/31/2006 3:46 PM:
Powerheads like quiet one 3000 give you more water
movement per watt of electricity than external pumps.

Yes, that's correct. Because of their design, they will use less
electricity. External motors don't use the vibrator pump method, but are
actual motors that continue to move the shaft in the same direction until
it gets into the next position, and then the next electrical contact is
made, forcing it into the next position, and so on, and so they use more
electricity.

Wayne Sallee
Wayne's Pets