READ BELOW: My hubby's question he wants me to ask is how important is aeration in the winter???????
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Geo output fell way off, upon investigation, we found out that our pond loops had floated (5 loops / we have a 5 ton Carrier GT-PX system). The tech told us today that we have an aerator in the pond and we should not be running an aerator in the pond as it is causing stratification which caused ice to freeze around the loops causing them to float (our loops are stuck under the pond ice at the surface!
This is our second winter with the system, last year the geo just totally shut down (I had high electric bills with the heat strips) and in the spring 2009 they came back out and fluffed the loops and added a loop.

I do not want to compromise unhooking the aerator that we placed in our pond (for other pond and fish health).
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I may be way off base here, but I think the tech doesn't know what he's talking about. If anything, the aerator will help eliminate stratification by moving the water in the water column from where the aerator is located to the surface. That's one of the reasons why the aerator is in the pond, to help destratify the water.

The only thing that could throw a curve into it is if the aerator was in the deepest part of the pond, on the bottom.

If I'm wrong here, someone let me know and I'll delete the post.

IIRC aeration can potentially degrade geothermal pond loops by the same supercooling mechanism which can endanger some fish. The aeration diffuser/airstone should probably be moved to shallow water for the Winter.

The loops I would say were floated down right next to the airstone which is in the deepest part of the pond. Moving the windmill is out of the question so it sounds like I need to add some hose and string the aerator to the lower side; in general, will this still help aeration of the bottom of the pond in the deeper end??? Or, I could do a dual airstone with a splitter and block off one side in the deep part in the winter and just keep the air hose to the lower end open in the winter. And second I need to get the loop installers to come back and properly weight down the loops so they do not come up to the surface again.

The dual airstone would be the easiest route to take, I'm going to do that this year when I put the diffuser in deeper water - I'll shut the air to that one off during the winter and run the one in 5' deep water for the winter.

I'm getting confused here (nothing particularly new and I have a tendency to reside in a land of confusion).

Wiki definitions:

Stratification (in the earth sciences) is the formation of water layers based on salinity and temperature.

Destratification is a process in which the air or water is mixed in order to eliminate stratified layers of temperature, plant, or animal life.

I would think for a Geo Thermal system to work well you would want Stratification. Isn't that what a geo thermal system relies upon - the temperature differential? And if that is true then I would think that an aeration system could impact a Geo Thermal system.

In this particular case though my ignoramus guess is that the pond loops floating to the surface were causing more issues that the aeration system. Shouldn't these loops be weighed down or something?

I for one appreciate all of the geo thermal posts on this site and follow the discussions.

Wow! I am glad I am in a state where I don't really have to worry about aeration in the winter time. Sounds to complacated and risky with all the freezing of air lines and splitters and high electric bills!

JHAP:

I'm really interested in the Geo thread as well, as I'd like to go that route to get away as much as possible from the Utility companies. With Mark being in Indiana, that doesn't bode well for me. A neighbor had a heat pump installed and it took them almost 6 months to get it running properly. I'm not sure if the installers are trained properly in Geo system sizing, installation and operation, much less troubleshooting!

I figure that the more that I learn about Geo, the more intelligent questions I can ask about the system when it comes time to ask for quotes.

I think you've hit the nail on the head Esshup - finding an design and installation company that knows how to properly design and install the system.

Here out west I am mostly interested in a Geo Thermal system to cool down the hot summers (in 2006 we had several instances of 100+ temperatures). To keep a house in the 70s air conditioning would run probably from the middle of June through August almost non stop.

When we build our house up north we wanted to go as green as possible. Solar/wind power, geothermal, etc. Ultimately I don't know how much the budget will support, we'll see when the time comes.

I'm told that this usually happens in Ponds further North (but I did find another forum where someone in Illinois had the same exact problem and also had aeration). Problem lies in the loops--our thoughts at present is more weight on the loops, even thought the weight was correct--just not correct for my particular situation. We will put a splitter for two arerator heads in the pond so we can leave the one on the deep side in summer and switch to low side of pond in winter. Mind you, the loop installer IS reputable to the area...the odds of this happening were probably not high--when the tech called him, he knew EXACTLY what had happened. I hope my posting this will help others who are looking at pond loops to take a total look at the WHAT IFS, are you aerating?..........

MarkECIN, You may have addressed this already in some past posts that I did not do a search on. What is you reasoning for winter aerating in your area, Cold water fish, very mature pond, past problems?What size is your pond? Is your mill a Koender 1.5 cfm model.Sorry for all the questions but we've been putting aeration in looped ponds for the last 10 years and have not had this encounter.Have done may pond clinics with Geo installers and Power Company involvement and this has not been an issue when the question has arisen about winter aeration.I cant imagine the factory Koender type airstone that produces large bubbles and lifts perhaps 600gpm in 14 ft of water @ 1.5 cfm super cooling your bottom water unless your pond is real small,and you have lots of constant wind. I may be missing something here but think something else may be in play.

MarkECIN, your posts are helpful and I didn't mean to imply that your installer was not reputable. Many of us are following these Geo Thermal threads because we are considering using them in the future. I'm interested in the cost savings and payback period, and good and bad stories. I believe these posts help all of us.

Thank you for your input as well Ted.

As for me, I do not aerate and have no plans to at this point. When we eventually build our house I plan on using a geo thermal system as air conditioning in the summer. It gets quite hot at our place in northern California during the summer months. I don't know whether an aeration system would cause issues with a geo thermal system at our place or not. Ted is one of our top experts when it comes to aeration systems so I'd be inclined to believe any input that he has on the subject.

I made a contact on Carrier with some basic bottom water temp questions, winter water circulation at different temps and the weights needed on the loops. Im curious too on this situation.(and its a slow day here) Hope they reply !!If not Ill call them.

I truly do appreciate all y'all help. Hubby and I are at a loss that this has happened. I want the proper fix, "don't blame the aerator." Ted Lea I would be very interested in what Carrier tells you. We put aeration in because we didn't want the pond bottom to get stagnant and everything I read led us to believe that aeration was a good thing for the pond and fish and in the winter kept the pond from freezing over. Sure, I can move the hose to get the stone in the low end, but I question whether that is really what caused the loops to float. Ours is a one acre pond, windmill is 20' up, I'll check on the cfm and get back.
Jeff,I'm not offended. The HVAC company people are reputable and I believe are just as much at a loss as me. I'm starting to believe these loops have been the root of my problems with our geo system all along--one way or the other.

I see some of your posts on the Geo Exchange Forum, I find it interesting all the technology involved but all the varying opinion of weighting the loops. I dont see a downside to "anchoring" them down and then if the system ices having the internal system prevention do its job.I think there is some good information on that site.I do not have any winter pond aeration systems operating that has an Airstation near the loops (but not for that reason) I always suggest having a winter Airstation in the shallow section even with cold water fish so your pond can stratify from 39F on the bottom to 33F just under the ice.Rarely in a small pond (1 acre or less) do I agree with the many publications that open water in midwest and northern climates is a good thing.I think the idea of gass exchange being needed in the winter with risking a sub 39F bottom temp is not worth the gamble.One of the things that has changed over the years is diffuser technology and the ability to move massive amounts of water compared to older technology that just made "bubbles" So I believe that aeration in some past situation may now have a problem with todays high volume designs.I only winter aerate if I have snow cover for 4 weeks and then just enough to open an area to re-form clear ice.I run a windmill with the Koender 7-9 inch airstone in my small pond for winter only. I have a bypass valve on one of the legs that will exhaust to the air when I dont want aeration. Consider adding a splitter and an exhaust valve on yours and putting another diffuser in the shallows.Unless you have 3 plus cfm you will not be able to run both in the summer and even at that you will need a lot of constant wind as the compressed air will want to travel to the path of lesser resistance.Outdoor Water Solutions had a display at PB3 that had an electric unit kick in when the wind was not present that may have some merit.Keep in mind that sunlight is the key to oxygen production and not air bubbles from diffusers.I consider ice a needed blanket for warm water fish and open water in small pond a means of letting the heat out.Ill call Carrier today if they dont mail me back as I am curious on their take on the loop weighting and excessive freezing.(sorry about the long post)

Appreciated Ted...the weighing part has to be addressed as this could potentially happen again (probably will). And I do plan to do what you are noting above but just not convinced I am the problem and that the weigh down of the loops by whomever designs these need to better looked at and a more preventative solution design(that keeps the loops down).

I believe you posted that you measured the pond temp at the depth you thought the loop was at and the water temp was 35F.
Assuming the heat is available in the ground the water should be 39F which is the temp of water at maximum density. There is a full load heating capacity reduction of 12% with a change entering water temp (EWT) of 40F vs 30F. Data is from a Climatemaster Tranquility 27 5 ton Geo unit. I believe this unit is re-badged for Carrier. Setting aside the issue of fault regarding the icing. If turning the aereator off or moving it translates into an increase of 4F EWT it's going to put money in your pocket.

The installers have stated that ..."need to not run the aerator in the winter."

It has always been our intent to have a healthy aerated pond; the windmill was here before the geo. It was never our intent to compromise our pond/fish health. We could aerate in the low area in the winter vs the deep where the geo loops were installed next to our airhead, we could do that...but now becaus I have a one acre pond, they are of the opinion--no winter aeration at all.

Had we been told that aeration can cause loops to float up, we would not have allowed loops in the pond but had them installed in the ground.

Thoughts? Now I have a problem.

This may have been covered above, but I fail to see how aeration could cause the loops to float up. Mix the water and lower the temperature, making it harder for the geothermal to work, sure.

You don't really need aeration in the Winter except to avoid Winterkill WHEN you have snow covered or very cloudy ice for an extended period. This would certainly be in excess of one week. Why don't you put a manual release valve at the windmill and open it up in the Winter, except for maybe 24 hours or so (or until a hole melts) when you have had light-blocking ice on the pond for over a week. Maybe shut the valve to aerate on Saturday and Sunday under those conditions, and close it during the week. If you can also move the airstone/diffuser to shallow water in the Winter, that won't hurt the Winter aeration OR the geothermal either.

P.S. I see Ted covered all this already with more depth and expertise.

I will take y'all suggestion and this summer do some splitters etc...I just wish they'd told me this in the beginning and not had to deal with loops at the surface...their take is as follows....

..."Aeration turns the pond water and makes it so there is no difference in the water temperature at the different depths of the pond and the loop becomes a block of ice. When that happens the ice floats to the top taking the loop with it.....Ice is very buoyant."....

I hope any of you looking at putting geo loops in your ponds are reading this.......

So they are saying that the geo system takes so much heat out of the water that it freezes in the loop, then floats? Or are they saying that the loops are so cold that they freeze the pond water around the loops, therefore they float up?

Unless someone else proves to me (or I should say explain to me) otherwise, I say B.S.

edit:

O.K., I looked. A cubic foot of ice weighs between 57 and 59#. A cubic foot of water weighs 62#. So for every cubic foot of ice, it will lift 3# to 5#. How much weight did they use to keep the loops on the bottom is the next question.

We are.

You betcha!!!

My guess is these loops are going to float with or without aeration. That windmill with an airstone "does not can not" lower the bottom temp and eliminate stratification in the winter in this pond.These loops have to be under weighted and perhaps have the coils not spaced correctly within the loops. When the coolant is 26-30F it is going to freeze the water surrounding the pipes no matter the water temp.Weight them correctly and you'll be good to go.Theo is on target with the winter aeration approach for this pond.

esshup...we have 300' coils, 6 of them now...originally 5, they added one additional coil this past spring when they came out as there weren't enough spacers and the geo system wasn't geo'ing. Each coil has 2 concrete blocks holding it down; they tell me this is by Carrier guidelines - 300' require two 4"x8"x16" blocks (19 lbs).

I have yet to have anyone answer me on why the compressor was frosted over; we were told to let it defrost; next day it ran fine for them only to discover the floating loops.

One wonders if the extreme weather we had part of the month of Dec/Jan with really cold low digits played in this loop problem...IMO i still think it's the loops--oh well.

It's my understanding you have a probe for measuring underwater temps. I would check the calibration on the probe/gauge setup and assuming it's safe to go out on the ice, go and take some measurements.

You can use an ice bath with some ice cubes and a little water in a bowl to get a single point verification @ 32f.

Plot a profile of temp vs depth with and without aeration.

I would think the pond would start to stratify after a week or two after removing the source if aeration were actually causing the pond to mix.

You posted a few weeks ago that you had a 35F bottom temp. Assuming that was an accurate measurement, something caused that. It should be 39F. Perhaps you were right up against a loop or perhaps they had already floated.

I don't think the single digit temps could have anything to do with that assuming you had ice coverage insulating the pond and protecting it from wind.

Jist of things. Opinions?
Bottomline - loops have to come out of pond. Looking at horizontal pipe & trenches in yard.
Loop installer doesn't want to chance, nor the HVAC who hired him, the chance of loops floating up again even if we moved the windmill aeration to the low side and used is sporatically in the winter. He feels there is a 60/40 chance they will float again. As is now, probably will kink when sinks and has to be redone even if left inplace. ITO: NO aeration. IMO: I will aerate for fish and healthy pond.
ITO: We share fault (1/3). IMO: I hired professional to design/install this system.
I was just another homeowner, wanting geo vs my large LP bills, having talked to a couple of HVAC and because the one I choose didn't realize the windmill right by edge the pond that was aerating was bad. If you look at the Carrier paperwork they sent me last week and I also was given at the geoexchange site, clearly states "In the north, an ice cover is required during the heating season to allow the pond to reach an average 39F (39C) just below the ice cap. Winter aeration or excessive wave action can lower the pond temperature preventing ice caps from forming and freezing, adversely affecting operation of the geothermal loop."
IMO: They should have caught that and had they told me in the beginning, we would have put it in the ground (we just didn't want to tear up the yard back when).
To make things worse, I got my electric bill last week, $650.

Wow, sorry to hear that you are having all of these problems.