Is there too much oxygenation?

[Mucky_Waters]

Possibly.
The thing about having a hot motor pushing air into a cold hose is that somewhere along the hose length the air is going to cool and condensation will form. I don't think the type of pump matters that much.

I do, and that's probably why you won't find any fisheries using diaphragm type aerators.

Also, I don't think those diaphragm aerators are capable of producing enough pressure of forcing the air to much depth.

 

[brokensword]

I was referring to the ice, which could be far below freezing.

but the water below can't be less than 0 C, or freezing...

 

[brokensword]

Also, I don't think those diaphragm aerators are capable of producing enough pressure of forcing the air to much depth.

true dat

 

[MitchM]

It was enough to have the water look like it was boiling through those 2 12 inch diffusers from a 5 foot depth.

 

[brokensword]

It was enough to have the water look like it was boiling through those 2 12 inch diffusers from a 5 foot depth.

but Mitch, isn't that what you wanted in the dead of winter? Boiled haddock? heh

I think if it could put out enough force to keep that hole open, and NOT from the bottom but near the surface, say 18", it should have worked for you. But apparently, you're operating in less than 10 C, which we all know means you HAVE to switch to underwater pumps and cattle trough heates as well as regular heaters and you'll need to invest in cattle panels that are heavy enough so the wind doesn't blow them down...

heh, how ARE your fish doing without all that stuff, Mitch????

 

[Mucky_Waters]

but the water below can't be less than 0 C, or freezing...

Nope. Not in pond water anyway, otherwise it will turn into ice.
The colder the ice gets the faster it can cool the water but once the water approaches 0 c it will start to turn to ice. The barrier between the ice and water at the surface will be in a constant state of flux, the ice trying to freeze the water and the relatively warmer water trying to melt the ice. Whichever one is a bit colder or warmer will determine the victor.

Anyway, I've learned a bit about pond breathers, that they actually have little pumps in them.

But I still think aerators are the best bet for larger ponds or lakes. It is the air that gets trapped under the ice creating more surface area to react with the water that makes them more efficient, that and the fact that that trapped air under the ice also helps insulates the water from the ice that wins it for me, not to mention (or maybe to deliberately mention ) that this seems to be the method that the fisheries use to prevent winter fish kills, and not some form of pond breather, that wins me over.
For small ponds, I think those pond breathers might be quite adequate, but for larger pond applications I'd still recommend a robust aerator.
Thanks for the debate guys.

 

[MitchM]

I don't know why you think that it's a good thing for air to get trapped under the ice.
Ice may be theoretically porous, but it has it's limits.
At some point the pressure will build up and no further fresh air will enter the space under the ice.
I'm thinking my fish may be toast at this point. I can't even drill a hole to release the gas buildup.
Hopefully my organic load was minimal going into this winter.

...

Anyway, I've learned a bit about pond breathers, that they actually have little pumps in them.

...

Thank you. That's more research than TOP EXPERTS do.

 

[Mucky_Waters]

I don't know why you think that it's a good thing for air to get trapped under the ice.
Ice may be theoretically porous, but it has it's limits.
At some point the pressure will build up and no further fresh air will enter the space under the ice.
I'm thinking my fish may be toast at this point. I can't even drill a hole to release the gas buildup.
Hopefully my organic load was minimal going into this winter.


Thank you. That's more research than TOP EXPERTS do.

Just when I think I'm out they suck me back in. LOL
Mitch the air trapped under the ice the air is going to be in constant contact with the water thus allowing more time for air exchange, which is one reason just running an aerator alone doesn't allow for adequate oxygen absorption. For adequate oxygen absorption, you need two things, surface exposure and time for the oxygen exchange to take place. Air trapped under the ice provides both.
Also, you can surely see the benefit of having an insulating layer of air between the colder ice and the water in your pond?

As far as the pressure building up enough to prevent further air from entering, I don't think that is possible. Ice always has minute cracks that would allow air to escape, and the more pressure under the ice the more cracks would form or increase in size. Certainly, it doesn't seem to be a problem with fisheries aerators, in fact, I would say the opposite might be true in that the air being forced in might cause larger fissures and cracks to form in the ice thus allowing too much of the trapped gas to be released thus reducing the effectiveness of having that air trapped under the ice.

 

[MitchM]

Just when I think I'm out they suck me back in. LOL...

I'll let you go for now.
I need to quantify this ice permeability thing.

 

[brokensword]

maybe there's some research on ice pressure/thickness limits and/or if ANY of this forced air gets trapped at all. It would seem IF it did, either the water absorbs it (a good thing) or it escapes through the ice (but I wonder how fast/much ice can do this as there have to be limits) or there's pressure put back on the aerator+hose+pump. I know when my aerator died, the tube was still attached, the pump still running but no air keeping a hole open, hence I figured the line got pinched. Which meant my hose prob had a hole in it? Or with no air out, no air was sucked in, creating a stalemate of function?

 

[brokensword]

I'll let you go for now.
I need to quantify this ice permeability thing.

Mitch; found this. And the pic of fish going to the top for trapped air makes me think it is more beneficial than I thought.

http://www.indiana.edu/~clp/documents/water_column/Water_Column_V25_N1.pdf

Michael

 

[MitchM]

Ok, so;
Gas permeation through ice is almost non-existent.
CO2 moves through ice at -9.5c 2 million times slower than through liquid water
O2 does not move through ice at all.
The inter crystalline brine film the paper refers to includes impurities found in water.
http://onlinelibrary.wiley.com/stor...79&s=016324f8e11804e4efef99e258cc5fa9379c4c65

Mitch; found this. And the pic of fish going to the top for trapped air makes me think it is more beneficial than I thought.

http://www.indiana.edu/~clp/documents/water_column/Water_Column_V25_N1.pdf

Michael

Yes, that shows the importance of submerged plants in a pond. (algae included)

.

 

[MitchM]

That tells me that even if you do manage to pump air in under the ice, at some point the gases in the air trapped under the ice and gasses in the pond water will equalize and the pond inhabitants will still eventually suffer from lack of oxygen. (unless you have submerged plants/algae that can provide the O2, along with a source of light)

 

[brokensword]

Mitch, do you have many/any submerged plants in your pond? I'm now into year 2 of trying to get a herd of hornwort to become a forest and this spring, will add more if I find the inhabitants of my pond have been over zealous!

So, if the ice won't let O2 escape, do you think there's actual fractures that develop or is the pond/lake truly sealed until the ice melts? And if it is sealed, where does all the additional O2 go when the hole freezes over?

Much of what I found had to do with air infusion systems as being the best course of action. And, they tend to focus on getting a flow, bottom to top. I'm thinking in our backyard ponds, without the stratification, that this flow might not help? Not sure, actually, but from what I remember reading Bass Pond forums, they had issues with fish kill when aerators were placed at the bottom and not near the top. It's mainly why I've been advocating a higher elevation.

There was also emphasis on getting light through the ice and keeping the algae going strong as THE source of any additional O2.

 

[MitchM]

Other than algae, I don't have any plants.
I'm hoping to take out my liner this year and replace it with a bentonite layer and get some proper submerged plants and marginals around the edge.
I really don't like having a liner.
I didn't find anything on fractures. I'll keep looking.
I think if aerators are located at the bottom for the whole year, the pond should be fine over winter. I think that if aerators are only used at the bottom during the winter, H2S is stirred up and degrades water quality.
If O2 is continued to be produced by plants under the ice, then the water will become saturated with O2 but not to the point of reaching dangerous levels. So, the fish will be fine, even with a solid ice cover as long as there is a proper fish/plant ratio and not a lot of decaying organic material.