Rick,

One year I did buy a Luft pump from drsfostersmith.com
which is pretty powerful, but other air pumps I get I
usually get from Wally-World, and I buy the $9.95 unit.
I also use a T-connector and bring both of the outlets
into one hose and add my airstone.

Tom L.L.
-------------------------------------------
Rick wrote:
Tom
How big of a bubbler do I get? Looked a Wally Word and the biggest one is
for a 40 to 60 gal tank. my pond is give or take 1200 gal.

"Tom L. La Bron" wrote in message
...

Rick,

I don't have that much problem with total ice cover and
according the Farmer's Almanac this winter is suppose
to be mild in my region, but there have been winters
with total solid ice cover.

Over the years I have checked trough de-icers and they
usually run 1,000 to 1,500 watts and the thermostats
that some of them have turn on between 38 degrees F. to
34 degrees F. depending on the brand. Needless to say,
the cost of running one can be high, so I have used
airstones.

The airstone may not keep a hole in the ice but it will
cause an escape for the air through the ice which is
what needed. One of the years when the ponds froze
over sold I came out and told myself, "what a waste,"
because there was no hole. Upon closer inspection I
found that the air was making its way up through
channels created as the ice froze. One of the
important things that you have to remember when using
an airstone is to have the airstone just below where
the thickness of the ice will accumulate, you don't
want to disturb the water layers at the bottom of the
pond, so keep it high in upper level of your pond. I
have switched over to an air blower so my airstones
this year will only be about 6 inches below the surface
of the water, which for me is more than enough.

Good luck with what ever technique you decide to use.

HTH

Tom L.L.

Rick wrote:

I have bin told to just put one of those heaters that the farmers use to
keep fresh water for there cattle from freezing in to my pond. They

have a

built in thermostat and only turn on when the water reaches 33 or 34
degrees. I have also bin told that you should not let the pond freeze

over

because of the gas build up and not the lake of oxygen. Are you saying

that

I sill should put in a Bubbler?




"George" wrote in message
t...


"Ka30P" wrote in message
...


Roark did a bit on water and winter in response to a question and it

makes a


pretty interesting read.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~
From: Roark7
Subject: Bubbling bottoms and super cooling
Date: 1997/10/31

David Swarbrick wrote:



Bubblers are recommended for maintaining an ice free portion of a pond
over winter, and maintaining good oxygen levels. I have also seen it
suggested here that it should not be placed on the bottom of the pond,
but raised so that the circulation it induces does not disturb the

water

at the every bottom because this merely results in the very cold water
by the ice being distributed all over.

I question this.

Yep... And I don't blame you one bit. I had the same doubts and

voiced the


same arguments that you shortly share because it *is*

counter-intuitive...


until you start looking hard.

Actually, if your pond is deep, like mine (45 inches or more), the

circulation,


which goes from bottom to top, will draw the residual warmth in the

ground

below


the frost line to the upper levels of the pond, and moderate the water
temperature. I ran a bubbler from the bottom all winter last year and

only had


ice two days (less than 1/8 inch thick, at that, and only on one end).



First, warm water rises, and cold water sinks. The water at the bottom
will always circulate if there is a temperature difference. Frozen

water

floats. I suppose there must be a point just before water freezes

where

the situation turns on its head, but I assume also that this is only

at

the point very near freezing.

I had major questions about the physics aspect of this whole "winter

pond"


thingy as well. I did some asking and a bit of research and came up

with

three


things which cause the inverse stratification effect. These are, in

ascending


order of importance:

- The native heat of the earth
- The physics of water going from a liquid to a solid
- Surface cooling due to winds and cold air.

I'll rattle through each contributing effect in detail below:

- Heat of the Earth:
It turns out that the earthern bottom of a 4-foot deep pond stays right

around


34-38 degrees even though the outside air temperature drops much lower.

The


simple reason for this is the Earth is slightly exothermic.
As you dig down
you hit a point where more heat is being released by the earth than can

be


pulled-away by wind, night sky, etc. This is why you bury water pipes

below


the "frost line". This heating effect is small in ponds, but it *is*

there.


The earth *is* pumping a bit of heat energy into it all the time. The

other


effects (below) tend to magnify this effect into something useful by

keeping


this slightly warmer water on the bottom.

I will add here that the residual heat of the earth is called the

geothermal


gradient, and varies from place to place, and increases with depth. But

at


shallow depth, it is affected by surface temperatureand wind chill. For
instance, at the latitude where I live (38 degrees), the air in a cave

stays in


the vicinity of 54 degrees F, depending on air currents within the cave,

which


depend on the connectivity of cave passages, and the number of surface
entrances, all of which can affect the transfer the heat to the

surface,and visa


versa. Travel north of this latitude, and the temperature is lower.

Travel


south of this latitude and the temperature is higher. With regard to

ponds, the


surface temperature has an effect on the soil, but only to within a

certain


depth. That depth is called the frost line. Below that depth, the soil

will


not freeze, but will retain it's residual warmth, and increase with

increasing


depth. The frost line varies with latitude. At my latitude, the frost

line is


at 22 inches. In order to keep buried utilities from freezing (such as

water


lines), the local building codes required the utilities to be buried six

inches


below the frost line, at 28 inches. If you live at 38 Degrees north

latitude,


and your pond is 45 inches deep, then the bottom 17 inches will not

freeze

(unless, of course, you have an abnormally cold winter, in which case,

your pond


can actually freeze solid, but this is rare in most cases). Lat year my

pond


only had a small surface crust for two days, and then stayed ice free

the

rest


of the winter.



- Physics of Water:
It turns out that water doesn't move upwards because it is "warm" nor

sink


when
it becomes "cold". A little thought reveals this behavior is strictly

a

function of density. Warmer water *tends* to be less dense so it

rises... but


this isn't gospel. An interesting kink in the water density -vs-

temperature


curve shows-up just prior to 32 degrees F. At the pre-freezing point

(32.8


F), water undergoes a major density change. As it cools it becomes

*less*


dense than water which is just a fraction of a degree warmer. This

difference


is fairly large. Being lighter than the surrounding water,

near-freezing

water


*rises*. (This is one reason frozen pipes tend to burst. The density

of the


water decreases, the mass stays the same, so the result is volumetric
expansion which splits pipes with ease.) The degree of final bouyancy

is


controlled to a large part by the dissolved oxygen content of the

water.

The


more dissolved O2, the greater the expansion once the freezing point

has

been


reached. Since water at the *top* of the pond tends to have a greater

O2


concentration, this further contributes to stratification.

Near-freezing


water moves toward the surface, and then, having reached the surface,

freezes


completely.

Unless, of course, you draw warmer water up from below, which is why I

place the


air stone at the bottom in the winter. Some have suggested that drawing

the


warmer water from the bottom to the top will cause the temperature of

the

water


at the bottom to drop. But that doesn't happen if the pond is below the

frost


line because the surrounding soil will release it's residual heat into

the

water


as the warmer water is drawn towards the surface. Of course, if your

air

supply


is outside, and the temperature gets very cold, pumping that cold air

into

the


water could affect the water temperature. The overall temperture of the

pond


may drop slightly, but usually not enough to adversely affect the fish

unless


the air temperatuere stays below freezing for a long period of time (in

which


case, you might consider keeping your air pump indoors and running the

hose out


to the pond. I know a guy who has installed a buried air hose to his

pond

from


his basement, where his air pump is located. So in the winter, he is

actually


pumping heated air into the pond).



- Surface Cooling Effects
This one is pretty obvious, but its worth restating to put it in

context.


Given a sub-freezing day and a brisk wind, its a simple matter to pull

more


heat from the top layer of water than can be replaced by natural

convection.


Once the top starts to freeze, heat loss to ambient and basic water

physics


insures the top will *stay* cooler than the bottom. If this wasn't

true,


you'd never see a thin coat of ice.... the pond would instead just hit

a

point


where the entire thing suddenly became a solid chunk of ice.



It seems to me that if the air being pumped in is warmer anyway (in my
case, from inside an unheated shed), then the balance will be about
right.

Your idea about pumping warm air into the water isn't a bad one, but it

will


take a lot of warm air to make a dent in the ponds temperature.... far

more


than you could reasonably produce.

That is true. However, as I stated above, pumping cold air into the

water

can


adversely affect the water temperature. So, the warm air won't heat the

water,


but will simply prevent it from making the water colder than cold air

will.


Pumping a large amount of air in would
also create currents which the fish would need to fight or at least

adjust


for. Hibernating fish are in no position to do this and forcing them

into


this situation uses energy they will need during the rest of the

winter.

For keeping a hole in the ice however, you could likely use this

warm-air idea


to your benefit. Put an airstone a foot under the water and run warm

air to


it. Bear in mind that you will lose lots of heat in just a short run

between


your shed and the airstone.

An alternative would be to purchase an electric deicer for about

$50-$60:

http://www.pondsolutions.com/pond-heaters.htm



Also if the problem with water under ice is the lack of oxygen and

build

up of waste products under the ice, then the more chance the bubbler

has

to oxygenate the water and take away the foul water the better.

Whether you use a de-icer or not, it is always a good idea to add air to

the


pond in the winter time for the reasons you state above.



The oxygen demands of fish near the freezing point are very, very low.

This


is
a good thing because I've got a feeling there isn't much oxygen

available once


you near the peak of winter. Fortunately, decay and decomposition of

wastes


by bacteria has nearly stopped as well which relieves a decent portion

of the


oxygen load. Very little oxygen is needed in a winter pond.

Unless it freezes over, in which case, there is no oxygen exchange, and

the fish


could die.



During a really *cold* winter, I think the idea of a full-blown bubble

system


would tend to upset a natural balance which Nature clearly went out of

her way


to establish. Having said that however, I can see a very definite

*benefit*


to using such a system as the air temp starts to push into the upper

30's and


40's. By introducing additional air and inducing water motion, you'd

be


putting lots of needed oxygen into the water as well as helping the

pond

to


absorb ambient heat. Fish coming out of their winter sleep wouldn't be
oxygen-stressed as well as being thin, worn and badly in need in of a

shower.


From what I'm given to understand, most fish have no problems

during the


actual *wintering*... its the *transition* from hibernation to normal
metabolism which gets them. Your bubbler could be a great tool during

that


transition period.

It is also important to transition your fish to food that is easier to

digest


when preparing the pond for winter as the microbes in their gut that

helps

in


digestion will eventually go dormant.