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Re: [APD] Filter versus Pump



I don't rely on circulation alone from a filter. However,
if all you're using is the pump and this has proven
successful with your aquarium, then there's no reason why
you can't replace it with another pump.

You've got lots of choices for pumps and opinions on them 
will vary widely. Decide what size of pump you need and and
whether external or submersible. I recommend the Ehiem and
the new Quiet One pumps be among those that you consider.

If that answer is too brief for you, I'll say more. If you
search, you'll find complaints about just about every pump
you can think of. Generally, with the direct-drive,
permanent-magnet-rotor type of pump (the design that
Eheims, virutally all powerheads, and a preponderance of
aquarium pumps are based on), the most common complaints
are about noise and in a few cases, reliablity. 

The noise is usually caused by the slip fitting that
attaches the impeller to the shaft. It allows the motor to
get turning in one direction or the other without having to
turn the impeller-- as a rule, this type of ac motor
doesn't have a preference for direction of rotation. Basic
AC motors don't want to turn at all unless they get started
turning and so the slip fitting is necessary. More
expensive motors might have an extra set of stator coils or
capacitor to shif the phase to initiate start-up but hat's
generally reserved for much bigger pumps than we use on
aquariums.

Many of these pumps are designed so the chamber around the
impeller, the volute, will pump regardless of which
direction the impeller turns -- on these pumps you can see
that the outlet is at the center of the outside perimeter
of the volute. A few designs are preferential and the
output will be off to one side of the volute. The old
version of the Lifegard Quiet One is a good example of
this. So are the magnetic transmission pumps like the
Iwaki. 

The old Quiet One was truly a quiet pump but it came in
only one size, about 1000 gph and could be used only as an
external pump. An oddity in nomenclature is the Supreme
Mag-drive line of pumps from Danner. These pumps are named
Mag-drive but they are all direct drive pumps based on the
basic permanent-magnet-rotor design.

Curious hybrids are some but not all of the new Quiet One
pumps. I've tried five models from the new line. They come
in a variety of sizes and some are preferential for
direction of rotation. Despite the preference in rotation,
they all have the slip fitting. I haven't had any noise
problems with the smaller ones, but have experienced
clatter with the 4000 High Head, and the 5000 models. I
have found that if one of these pumps starts up with a
clatter, then stopping and restarting the pump stops the
clatter and then the pump runs relatively quietly. I
presume the clatter is due to the pump trying to rotate in
the "wrong" direction and causing the impeler to vibrate on
the shaft. The faint 60 Hz hum of the motor on the 400 HH
and 5000 models is louder than the old Quiet One model but
quieter than other brands of pumps I've tried as external
pumps. The new Quiet Ones can be used submerged or
externally (except the smallest model).

Among submersible-use-only pumps, the Eheims are extremely
reliable and I haven't come across a noisy one yet and I've
used about a dozen or so over the years. But they are
pricey.

This isn't much to go on but hopefully, plenty more
feedback on pumps is coming your way. There are a lot of
them out there. So many are based on the same basic design
-- it's the quality and tolerances in manufacture and the
tweaks in the design that separate the quiet and reliable
pumps from the chatterboxes and loud hummers.

Good luck, good fun,
Scott H.
--- "John T. Fitch" <JTFitch at fitchfamily_com> wrote:
> . . .
> So what I have left is really just a pump.  . .
 
> Now I'm wondering why I couldn't replace the cannister
> with a simple pump or
> powerhead.  The Fluval is rated at 260 g.p.h., and I find
> pumps that provide
> more flow than that at a quarter the price of a new
> Fluval.
> 
> Would this be a practical or advisable solution?  If so,
> would someone
> please recommend a reliable and *quiet* pump.  Thanks in
> advance.


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