Richard Tanzer wrote:

Dan wrote in :

Richard Tanzer wrote:

One seasonal advantage of a submerged pump, relative to a pump that
sits outside the pond, is that all the electrical energy that goes
into the pump is dissipated as heat into the water. So in the
winter, if your pump is drawing 100 watts of power, you are adding
100 watts of heat to the pond.

Actually, that would only be true if you had the world's most
inefficient pump, i.e., one that moved no water. A certain
amount of energy is 'wasted' as heat, but hopefully only a
small fraction of that consumed by the pump.


Dan, I believe you are mistaken. Even if I had the world's most
efficient pump, all the energy that goes into moving the water around is
lost to friction, i.e. drag forces. Otherwise the water would keep
accelerating as you continued to add energy.

Yes, the only difference is that the heat from the more efficient pump is
distributed more evenly around the pond, while the heat from the
inefficient pump tends to be conducted directly from the pump. The
inefficient pump will more quickly melt a hole in the ice :-)
--
derek

Richard Tanzer wrote:

Dan wrote in :


Richard Tanzer wrote:


One seasonal advantage of a submerged pump, relative to a pump that
sits outside the pond, is that all the electrical energy that goes
into the pump is dissipated as heat into the water. So in the
winter, if your pump is drawing 100 watts of power, you are adding
100 watts of heat to the pond.

Actually, that would only be true if you had the world's most
inefficient pump, i.e., one that moved no water. A certain
amount of energy is 'wasted' as heat, but hopefully only a
small fraction of that consumed by the pump.



Dan, I believe you are mistaken. Even if I had the world's most
efficient pump, all the energy that goes into moving the water around is
lost to friction, i.e. drag forces. Otherwise the water would keep
accelerating as you continued to add energy.

Because the water very quickly reaches a more-or-less constant velocity,
whatever kinetic energy is imparted to the water by the pump must be
converted to thermal energy in the pond.

Consider two 100 watt electric pumps submerged in a fish pond. The first
motor is highly efficient, 90 watts of energy go into pumping water and
10 watts are lost as heat in the motor. The second motor is far less
efficient, 10 watts of energy go into moving water and 90 watts are lost
as heat in the motor. From the perspective of heating the water, the
motors are equivalent. The only difference is whether the heat is
generated in the motor itself, or in the pond in turbulent friction
(vortices and eddies).

Ahh .. the wonderful world of thermodynamics.

Yup, you're correct. I was merely talking about the heat generated
by the motor itself, not the heat generated by the friction of the
water since that's pretty constant whether the motor is submerged
or not. Say, as in your example, a highly efficient pump only wastes
10% to heat, a 100 watt submerged motor is only adding 10 watts of
heat to the water over an external pump of the same efficiency, right?
In any case, every bit helps (except in the summer that is ). BTW,
any idea how efficient 'high efficiency' pumps really are? I haven't
a clue. Is 90% about right?

90%-95% is typically considered "high efficiency" for an electric
motor. Of course many manufacturers claim "high efficiency" without
providing data to back up the claim. Also the efficiency of an
electric motor can vary greatly depending on it's load and speed. And
of course the efficiency degrades as the motor or pump gets dirty and
worn.

But back to fish stuff. Do you think that my fish expend any more of
their own energy when in a pond with the pump running than when the
water is quiet? I've noticed that in the winter they congregate in one
end of the pond that has the least circulation.

- Rich

wrote in message
oups.com...

But back to fish stuff. Do you think that my fish expend any more of
their own energy when in a pond with the pump running than when the
water is quiet? I've noticed that in the winter they congregate in one
end of the pond that has the least circulation.
================================
The have to expend energy to stay upright then the water is moving. Why not
just keep a nice size hole open in the ice and allow them to "rest" as they
would in nature?
--

Koi-Lo.... frugal ponding since 1995...
Aquariums since 1952
My Pond & Aquarium Pages:
NEW PAGE: Aquariums:
http://bellsouthpwp.net/s/h/shastada...ium-Page4.html
http://bellsouthpwp.net/s/h/shastadaisy
~~~ }((((o ~~~ }{{{{o ~~~ }(((((o

"Koi-lo" wrote in
:


But back to fish stuff. Do you think that my fish expend any more of
their own energy when in a pond with the pump running than when the
water is quiet? I've noticed that in the winter they congregate in
one end of the pond that has the least circulation.
================================
The have to expend energy to stay upright then the water is moving.
Why not just keep a nice size hole open in the ice and allow them to
"rest" as they would in nature?

Keeping a nice size hole open in the ice is a challenge. Here in central
Wisconsin, in January it's not unusual to have morning temperatures of
about -10 deg F, with daytime highs of about 15 deg F.

My pond is only about 3 ½ feet deep at the deepest part. To keep the
pond from freezing solidly during a cold spell I have to heat the pond.
I have a small heater (25 watts?) that is intended to keep a hole open;
and that works just fine when the weather stays above zero F. But in
colder weather I need auxiliary heat. Last winter during cold spells, I
added heat by pouring a few gallons of boiling water into the pond every
morning. I was able to bore a hole in the ice that way. All but one of
my fish survived the winter.

This year I'm leaving the pump running to add some heat and also ensure
gas exchange.

It hadn't occurred to me that the current in the pond would stress the
fish. We've had a few relatively warm days, and the pond is largely ice
free right now. Perhaps I can move the hose to minimize the current;
I'll give it a try.

Well … the days are getting longer, and it's only seven more weeks until
pitchers and catchers report for spring training!


Rich

here in southern wisconsin not covering the pond means the fish go without food for 6
months. cover the pond with plastic and it cools down later, heats up sooner,
especially if it is in direct sun (mine isnt). 1600 gallons with 1.5 feed above
ground level, plastic, a 500 watt heater and a bucket filter and I fed my fish all
winter except 1 month. 2 years (knock wood) with no losses... also no meds needed.
this year I screwed up just got my plastic over just 1 week ago, but temp went from
40-49oF in 4 days and the koi are up to the top ... tomorrow I will feed them
lightly. Ingrid

Richard Tanzer wrote:
Keeping a nice size hole open in the ice is a challenge. Here in central
Wisconsin


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Solve the problem, dont waste energy finding who's to blame
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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any of the recommendations I make.
AND I DID NOT AUTHORIZE ADS AT THE OLD PUREGOLD SITE

"Richard Tanzer" wrote in message
...
"Koi-lo" wrote in
:


But back to fish stuff. Do you think that my fish expend any more of
their own energy when in a pond with the pump running than when the
water is quiet? I've noticed that in the winter they congregate in
one end of the pond that has the least circulation.
================================
The have to expend energy to stay upright then the water is moving.
Why not just keep a nice size hole open in the ice and allow them to
"rest" as they would in nature?

Keeping a nice size hole open in the ice is a challenge. Here in central
Wisconsin, in January it's not unusual to have morning temperatures of
about -10 deg F, with daytime highs of about 15 deg F.

My pond is only about 3 ½ feet deep at the deepest part. To keep the
pond from freezing solidly during a cold spell I have to heat the pond.
I have a small heater (25 watts?) that is intended to keep a hole open;
and that works just fine when the weather stays above zero F. But in
colder weather I need auxiliary heat. Last winter during cold spells, I
added heat by pouring a few gallons of boiling water into the pond every
morning. I was able to bore a hole in the ice that way. All but one of
my fish survived the winter.

This year I'm leaving the pump running to add some heat and also ensure
gas exchange.

It hadn't occurred to me that the current in the pond would stress the
fish. We've had a few relatively warm days, and the pond is largely ice
free right now. Perhaps I can move the hose to minimize the current;
I'll give it a try.

Well . the days are getting longer, and it's only seven more weeks until
pitchers and catchers report for spring training!
=====================]=
Rather than going through that why not just bring them in for the winter?
What about a kiddy pool in your garage for the coldest months of winter?
They hold 150g which will hold at least 10 to 15 goldfish for the winter.
--

Koi-Lo.... frugal ponding since 1995...
Aquariums since 1952
My Pond & Aquarium Pages:
NEW PAGE: Aquariums:
http://bellsouthpwp.net/s/h/shastada...ium-Page4.html
http://bellsouthpwp.net/s/h/shastadaisy
~~~ }((((o ~~~ }{{{{o ~~~ }(((((o