Pond Boss Forums AERATION Systems questions geothermal water cooling

I've been struggeling with high water temps in my small pond. 1/10th acre x 8 feet deep. I've been trying to keep trout, only with some success, even in NH. I can't afford a full depth well that pumps 24/7. I already have a small well that adds about 500 gallons of 54 degree water in on/off cycles.

Has any one gone the geothermal route by curculating water from thier pond through tubing buried below the ground to capture the cooling aspects and back to the pond?

Anyone know how to calculate the pipe size and lenght of run to cool the water to below ground temps, like a well would provide?

Hey Scruffy,

Recirculating the pond water is an interesting concept if there are some kind of self cleaning filters for debris or a grinder pump. I assume that this "geothermal" system would have nothing to do with cooling your house and everything to do with pumping water out of the pond, through the pipes and back in the pond a few degrees cooler.

What if there was a water source nearby that was a little higher in the water shed. You could run that same "geo" pipe and let gravity do the pumping. Just a thought.

Hmmm,

A Pondirador.

My natural water source is over a quarter mile away my only option is a a looped coil that brings the water back to the pond cooler. Being reading about geo-thremeral for house heating/cooling thought it might work on cooling my pond?

In that case, I would just aerate the groundwater and let it flow into the pond. Forget heat exchanging.

In that case, I would just aerate the groundwater and let it flow into the pond. Forget heat exchanging.[/quote]

The up hill water source would have to be fairly large to keep up with the constant flow whether it be a pond or stream. In either case it would still be subject to radiant heat from the sun, raising the water temp to what the pond already is. I was just brainstorming ideas that utilizes a geothermal cooling effect.

Scuffy,
You wouldn't be planning to utilize the same system to cool the house as well, would you? Considering the fact that a geothermal system adds heat to the water in AC mode.

Unfortunitly the running water source is not only not on my property but it is also down below the pond pool base. I wish water would flow up hill.

The water temp from my small well is @ 54 degrees. At some depth the ground is a constant temp. of 54 degrees. I thought someone on this board would know what the minimum depth would be? Then I could use the ground as a heat sink for cooling the water. A deep well is out of the question for cost at the moment and the geo idea my also be to costly.

I'm by no mean an expert, but I would guess under 6 feet and you'd have a pretty steady mean temp.

Did some on-line research and found you have to go below the frost line and in NH it is four feet deep. That puts the concept on hold for costs for me.

The stones that line my pond came out of the hole we dug for it. I would think I'd come across more large stones in digging a long trench.

You can also cool water via evaporation with a properly designed water fall.
I would think you could pull water off the top of the pond & return it 10 deg. cooler with the proper setup.

I'm in the process of building a waterfall. At the moment The water is being pumped out of the pond through a nozzel and cascades into the pond. Not great for cooling, but the aeration is good.

The waterfall is a labor intensive job and I can only work on it in bits and peices. It is going to have a pool at the top which will over flow down the rocks and into the pond. A drop of about 10 feet over after it is complete.

I control my aeration (pump and membrane diffuser) with a thermostat to manage temps. The thermostats are used by greenhouses to turn fans on and off at certain temps. I set the system to turn on when it is below 70 and off when it is above.

I checked the temps the other day and was pleased to find 70 degree water at 5-6' of depth. Temps at that depth last year were much higher, however, this has been a mild summer.

Also, last summer I tried pumping water directly to the bottom of the pond, which seemed to help keep it cold down there. The problem is that the water has to be aerated prior to pumping or you can build up poisonous gases.

Saw your old post. Did you ever figure out a way to cool water gerothermally? I thought your idea of burying tubing and circulating water through it was good - wondering if it works....

I LOVE this idea. I previously was looking at another thread on aerating without disrupting the thermocline.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=173127#Post173127

If you had an adequate geothermal system that was internally aerated, you would have aerated cool water in the summer in the depths, and in the winter you would have warm water in the depths. It would be theoretically possible to have warm and cool water fish successfully in the same lake year round. Think LMB, rainbow trout, and threadfin shad.

I think an interesting system might look a bit like the looping system below, buried, with the intake and outflow on opposite sides instead of the same side. If you had enough loops, you could create a high volume, low water flow system that would be adequate both for heating/cooling and aeration purposes.



If you had intake and outflows that emerged from the ground, took a 90 degree turn and faced down, you could limit the sediment and crap that would potentially get into the system and clog it up.



You place an accessible filter just before the elbow, an accessible above ground in internal pump, internally aerate the system, and you are there.

Another option is a partial recirculating aquaclture system for trout. Partial because you would need some well water to keep the temperature down and replace waste water, but not nearly as much water as you would need if your system was strictly flow through.

Smaller amounts of well water would be needed as you are recirculating most of the water in the pond. Not sure how large your pond is but smaller is better as far as volume and of course steep sides to keep warming down.

You would need a biofilter of which there are several choices all of which you can build yourself. I've built one and plan on building another type to test it's effectiveness. Before you biofilter you would need a mechanical filter of which again there are several choices and some if not all can be built yourself. I will be purchasing or building a rotating drum filter for a system I hope to set up in a Pole building in the next year or two.

Believe it or not your pond would be similar to a high end Koi pond with water being mechanically and biologically treated to produce clear water, but of course in the case of trout keeps temps down.

All of this can be hidden outside with some creative landscaping or put inside your basement (if nearby) or another small building.

Thanks Cecil.

Hmmm....I went looking at hypolimnetic aerators online.

I think the system I described above would have a lot of difficulties achieving adequate aeration. Bubble aeration just isn't very efficient, unless you are going to use O2 or O3.

You'd probably need a separate geothermal system, which I like because of it's simplicity and self contained nature, and hypolimnetic system. Total cost...a gajillion dollars.

The cost of a recirculating system for a small pond with home built components would only be a couple of grand tops in material costs if you don't have iron issues.I ran into someone on the Internet once that had trout in a pond with recirculating water. A flow through with Aerated well water minus the well would be about 200 hundred or less in plastic media and several buckets.

Remember you don't need much of a pond for trout as long as the water's cold enough with enough oxygen. Here's an example of a very small lined pond with up to 14 lb. golden rainbows at a farm in N. Muskegon, Michigan.





The think is you can build a small trout pond upstream of your large pond and allow the overflow to go into your bigger pond to keep it topped off.