By Steven Pro
With the increasing
popularity of sump-based systems and closed loop circulation, a thorough
discussion of external water pumps is warranted. External pumps have
several pluses in comparison to internal ones. External pumps usually
impart significantly less heat than internal pumps. This can be extremely
important for reef systems with their high intensity, high heat lighting
systems. Plus, many are more powerful than internal pump options. As
such, most larger aquaria are designed to incorporate at least one and sometimes
numerous externally mounted pumps to provide the majority of the displays
Sea Life Velocity T4:
Custom Sea Life
(CSL) went out of business a while back, but these same pumps are now available
under a couple of names, including Poseidon and Blueline. These little blue
pumps are super compact and extremely quiet. Their diminutive size is the
most striking feature when first seeing one up close. That is until you
touch one that is running. Man, do they run hot! I was literally
unable to keep my hand on the pump long enough to count to three, one
one-thousand, two one-thousand, three one-thousand. I couldn’t get past
two before I had to yank my hand away the heat was so intense. That
concerns me for two reasons. First, I am concerned with how much heat this
imparts to the water. Second, I am concerned with what impact this has on
the pump’s life.
E.G. Danner/Supreme Mag-Drives:
While a lot of
people know that these pumps can be used submerged, they also can be mounted as
an external pump. I have used a number of these pumps in this manner and
have found them to function just fine. They are very reliable, but their
strongest selling point is how inexpensive they are. They are one of the
cheapest pumps available! They do have their downsides though. They
are not the quietest pump. And, they likely impart more heat to the water
than other external pumps. Still considering their price and reliability,
they are an attractive choice.
The only other
potential problem people have with these pumps is salt creep. They are
prone to tiny leaks, resulting in some salt residue around the intersection of
the pump housing to the impeller cover if the o-ring is not seated in place
properly. This can usually be corrected easily enough by unscrewing the
four screws holding the impeller cover in place and reinstalling the o-ring.
Otherwise, maintenance is rather minimal on these pumps.
Eheim is another
brand known mostly for submerged applications but they may also be mounted
externally and they are extremely reliable whether used in or out of the water.
Unfortunately, that reliability comes at a price. Eheims are rather
expensive, especially considering the modest flow rates they produce in
comparison to their purchase price (see my Pump Comparison article here:
Still though, they do have their place. If I was looking at the multitude
of aspirating, needle wheel driven protein skimmers, I would favor those using
Eheim pumps because of their outstanding reliability.
Gorman Rupp Industries (GRI):
A GRI pump in use. A powerful
pump at a reasonable price. Photo by Steven Pro
I have not used
many of these pumps but I have been very pleased with the few that I have used.
They are relatively quiet, rather powerful, and reasonably priced. And,
for those who consider it important, GRI pumps are American made. I just
have not used enough of these pumps to feel comfortable recommending them just
yet, having only ever used four. But my limited experience would seem to
indicate that if one were to purchase one of these pumps, they would not be
I don’t have much
to say about these pumps. Iwaki are my default choice. They have
been making very reliable pumps for a long time. Most of the Iwaki line is
available in with either American made or Japanese made motors. I have
only ever used the Japanese made models. American made models are reputed to be
noisier than their Japanese counterparts. So, while the American ones are
considerably cheaper, that discount come at a price in terms of added noise.
The original Quiet One was a compact,
nearly silent external pump that produced a lot of flow.
Unfortunately, they were also prone to overheating and shutting down.
The new generation of submersible Quiet One's can be used submerged or
externally and are available in a range of sizes. Photo by Steven
These were the
first external pumps I used and as such, I had nothing to compare them to.
But looking back, they were not particularly quiet pumps. Actually, they
were relatively loud and annoying. They also seemed to rust rather easily
in the high humidity environment of an aquarium stand with a sump inside it.
These pumps are reputed to be fairly reliable, are available in a range of sizes
and are relatively inexpensive.
Rainbow/Lifegard Quiet One:
The current line of Quiet One pumps are built
for submerged or external use. The previous generation Quiet One pumps
were for external use only and are the only ones I am familiar with. They
were very quiet, as their name would suggest, and did not seem to impart a
significant amount of heat to the water. They were also rather compact for
a pump capable of putting out 1,000 gph. Unfortunately, the old Quiet One
pumps were plagued by overheating issues that would cause the pump to shut down
until it cooled off. Even though the new pumps are a completely new
design, I have not tried them because of my previous poor experience with the
There are a
multitude of external pumps currently available and I have only had the
opportunity to try a few. Still though, I have found several that I am
happy with and comfortable recommending to others. Japanese-made Iwakis are by
far my favorite brand of external pump. They have been around for a long
time and I have yet to be disappointed with one. For the price conscious,
my next choice is the Mag-Drive pumps. I have found them to be quite
reliable and their price makes them hard to pass up.