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Re: [APD] Pump help

--- Billionzz at aol_com wrote:
> >>>I've used the Quiet One 800, 4000, 4000HH and the 5000
> and the  design is 
> slightly
> diff when you get up above the 3000  model.<<<

> I'm trying to find a pump that runs quiet and the "Quiet
> One 3000" would  
> have been fine if the impeller  would have started back
> up after a power  outage.

A simple AC motor, like the 2-pole, permanent-magnet rotor
types used for many aquarium pumps, don't have a preference
for turning in one direction rather than another. But not
turning at all shouold happen only if the rotor is in a
position the puts the magnet poles perfectly between the
stator coil poles when the current first comes on -- the
odds are against this happening very often. and if it does
happen, the rotor will tend to vibrate, back forth in place
and the slip connection by which the impeller blades are
attached to the rotor will cause the rotor to turn farther
in one direction than another, thereby preventing a
"lock-up" at start-up. This is very old technology and for
a pump to lock up often has got to be a problem in the
production run.
> I bought a Eheim pump thinking that it would run quiet
> and while I'm sure  
> it's a good pump, it is anything but quiet.

Hmmm. Hum or rattle? If the output is severely throttled
down, that can cause some of these AC/permanent magnet
pumps to rattle. Otherwise, a rattle means the
rotor/impeller is not fitting properly -- which could be
problem of loose tolerances or excess lateral force on the
impeller housing.

> I'm thinking of returning the Eheim and getting another
> pump but I  don't 
> know what pump to try next I thought that the Eheim would
> be the top  off the 
> line.

They are certinly up there on the list. If you plow through
the pump info on The Krib, I think you'll find that for
every pump, there are some that found it quiet and some
that found it noisy. Seems there are rattlers in every
model. I've run a number of diff Eheim canistors and pumps
and they have been very quiet. YOur experience differs. I
willnote that if the connection to the input on an Eheim
1250 or 1060 pushes on the housing towards one side or the
other, that will tend to make them rattle. So it's hard to
say whether there is any clear choice for aquarium pump,

> What is the design difference between the "Quiet One
> 3000" and the  higher 
> rated Quiet One pumps?

The stator (the coils buried in epoxy inside the housing)
seems to be the same for all the models. Above the basic
4000 model, the impeller blades are designed to be run in
one direction -- the blades are a volute instead of
strainght and flat. This is more energy efficient and means
the chamber around the impeller can be better shaped to
guide the water to the outlet, which will be off to one
side on the impeller housing. On the 4000 and below, the
outlet is centered on the impeller housing, not favoring
either direction for the impeller. The 800 model differs in
that is employs a single shaft end bearing that is a cup
that rides on the end of a stainless steel pin. All the
others use two shaft end bearings on ceramic shafts. A
tried and true technology that Eheim perfected decades ago
and almost every other aquarium pump manufacturer uses
today. The exceptions are the large capacity external pumps
like, e.g., the Iwakis

The quietest mid-sized or larger aquarium pump I've ever
used is the old model of the Quiet One that had the
Grundfos motor. That motor was designed as a continuousl
duty recirculation pump for building hot water systems --
those systems the hot water piping runs in a continuous
loop back the the water heater and recirculation pump keeps
the water moving so that hot water is always available
anywhere onthe loop -- no waiting for hot water. That pump
was a heavy duty motor that was lubricated with a sealed
chamber of water around the rotor shaft. The motor shaft
extended beyond the rotor chamber as a direct drive for the
volute impeller. Replacing the motor rotor meant
dismantling the impeller chamber *and* the motor -- not
something the average hobbyist could do herself or himself.
And the Grundofs motor was expensive, with a cast metal
housing a capacitor that startup ensured that the motor
turned in only one direction. So when Pentair took over
Lifegard, the dropped that model for the new line of Quiet
Ones that are much more convetnional in design for aquarium
pumps, having a single-unit rotor/impeller assembly that
any hobbyist can replace.

You can still find the old models, even new, on Ebay and
Pentair might even have some still in inventory or know who
does -- it might be worth contacting them to find out. That
older model's output is more like that of the 4000HH than
the 4000 or 3000, but you could throttle it down quite a
bit without problems.

Good luck, one needs it when dealing with aquarium pumps,
Scott H.

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