Backyard Aquaponics
A place to discuss aquaponics

i want to raise RB trout this year, but worried i wont be able to keep the FT cool enough without an expensive cooling system. I am in N Idaho, and it can break 100F on some days. I understand trout like 59F?

I am already planning on having the FT in my garage where it is shaded. it can still get pretty hot in there But at least its shade and on a large concrete slab.

what i am thinking of is having the GB outside where they can get the sun and have the water lines run under ground perhaps a few feet. thinking of using sprinkler type pipe as it is inexpensive to work with and designed to be buried. but will it capture enough cooling from the soil? I wonder if there is a way to have a pump connected to a thermostat to cycle the pump whenever the water starts getting to warm?



also considering/researching a backup or perhaps primary power system using thermoelectric generators (TEG) whats your take on these?
http://www.tegpower.com/

its always bugged me how much waste heat is lost heating water and many other areas of our "modern" homes and this idea addresses it.

unless you were just running fresh water into the ft from a cool water deep well i don't think you could bury a line/tank deep enuff to get cooling for 100 deg days. you mite look into evaporative coolers but chilled water for trout is a hard one unless you spent money for elect chillers. you could extend your season a bit but i think coolers would be needed to keep year around.

I'm not experienced with keeping trout or geothermal applications, but I'll take a stab at this. By no means use my words as advice, please only use it for considerations... after all, when I kept trout I used ice... it was extremely inefficient.

Considering the average ground water temperatures, geothermal might be feasible. I had no idea Idaho got that hot! (according to my family that lived briefly over there, it's nothing but cold all the time. Then again we are from Texas and enjoy our cold weather 2 weeks out of the year.)

http://waterheatertimer.org/Shallow-gro ... e-map.html

According to that map your ground water is pretty darn cold. I'd be willing to bet it would be easy to keep trout year-round if you put them in a shelter that was very energy efficient, such as a hay-bale or cod house. Since it won't be a residence, you may not have to go through crazy building codes to build a structure for your fish tank. A fish house like that may be so insulated, you can keep it cool easily with just geothermal. If you had to use electric, it would be cheap to do so at least.

Also, an interested tid-bit, some trout live year round in central Texas because there is nature springs that feed our rivers - keeping them very cold.

I plan on using geothermal for both fish tank cooling/heating and for greenhouse cooling in the summer via an evaporative (swamp) cooler.

Hi,

Yes everything you say is correct. I am certainly no expert but I have done some looking into geothermal/ ground source/loop applications. I assume you are just talking about pipes, generally poly, not attached to a heat pump. Although even using a heat pump they are still quite efficient compared to other methods. Consider your air conditioner condenser on a hot Jul 90F day. With a ground loop your condenser would be working that much less because it’s heat exchanger is probably only 58F.

There is a pretty good description here http://en.wikipedia.org/wiki/Geothermal ... Horizontal . They suggest for a 3 ton/ 10kW cooling capacity 3 loops of 400-600 feet long, ie total 1200-1800 feet of ¾ poly pipe. This is the biggest stumbling block- a sizable excavation and initial expense. This is probably enough capacity to cool/ air cond an average house. So probably enough for the average FT if it is kept in the same sort of area and conditions. Although a body of water will change temp a lot slower than an equivalent volume airspace.

If I can add some comments. The map shows annual average temperatures. The temperature of soil 6+ feet, on any given day is generally something like the average daily air temperature from something like 3 months ago. So I wasn’t sure which city so I chose Boise from http://countrystudies.us/united-states/ ... /boise.htm as an example. So in this example the average, daily temp, ie ‘mean’ for Aug is 74 F. But your soil temperature is probably more like the May ‘mean’ of 58 F. This is because the soil at that depth has so much thermal ‘mass’, ‘lag’ or ‘inertia’ it takes that long, probably 3 months to stabilize to that temp. Of course this is not a hard and fast rule as there are many variables like soil moisture, evaporation, shade, temp differences etc.

Swamp coolers are certainly good, using a fraction of compressor air conditioners. Although of course they also have some limitations. They do use some water so if this is scarce or expensive resource where you are that is another consideration. They of course will only cool down to the ‘dew’ point. So in Florida, mid summer with 90F, 100% RH the dew point is 90F so they wont cool at all. It is also quite humid directly above FTs and GBs, especially on a hot day. Humidity is not too much of an issue in Texas.

Some thoughts for you.

so it sounds like if i go with a large enough body of water, even above ground, i shouldn't have to worry much about cooling? when you had to ice your water, how many gallons did you have? what was surrounding your tank?

digging that deep does not sound fun by hand. however, i am about to run some lines for my sprinklers in my backyard. wonder if 1ft or so would be much cooling? i would think the soil would play a big role in the temperature change per foot of depth.

my other thought would be to run the poly in a place where i plan to put my soil garden bed any how, so the watering of the beds would also provide cooling I would think....

Subterranean heating and cooling has been discussed many times... and some members have implemented it within greenhouses/sheds...

Here's a couple of links...

http://en.wikipedia.org/wiki/Ground-cou ... _exchanger

http://www.sunnyjohn.com/indexpages/shcs.htm

I tried it dident work

Just curious, what was your setup like?


I only had a few trout in a glass tank, not really for food but just for fun because I love fish

Also you might look at a vertical closed loop system. Massive amounts of hosing in a horizontal system is probably a lot better because it allows you to run water through at high rates, but require so much land excavation. I imagine vertical drilling to be cheaper to come by. My thoughts are to put a large pipe going down and a small one coming up. The water would flow down slow, hopefully reach its minimum temperature, then return to chill the fish tank. I'll have to post an illustration of what's in my head later when I get home. Once again I've never consulted an expert so take my words lightly.

There are certainly many reasons why this wont work.

For example if:

1. the pipes aren't long enough- capacity will be reduced, possibly to less than being inputed into system. ie more heat going into system from air surrounding FTs than you can take out with ground loop. In this case it may slow the rate at which your FT heats up, but not cool it. This is like trying to cool your whole house with a small window ac unit, it will do something, but nowhere near enough.

2. Pipes not deep enough so temperature difference is not enough to be useful. Again reduced capacity. Indeed this would also apply to the ground temp and FT temp out side the possible range of what you are trying to achieve.

It is all a question of heat in to heat out, or vice versa if you are trying to heat. Essentially temperature differences x surface areas at both ends.

Putting it mathematically, sorry to use metric but please feel free to convert yourself if you want.

1c change for 1 litre of water requires 1 W of heat (heat removed for cooling)
therefore 1c change 1,000 lts needs 1kW.
There is usually a time factor/ rate factored in here too
Ie 1c change per hour of 1,000 ltrs needs 1kWh
Of course the above is an over simplification because there is always losses and inefficiencies, which have not been considered, but you get the idea.
Some other things to consider-
• Slowing the undesired heat input/ or loss with insulation,
• A lot of people suggest burying, or partially FT’s and GBs,
• Also people suggest reducing flow through GBs during adverse temp times.
All stuff to consider.

wonder how much cooling effect the gravel grow beds would have? So far I am planing on half barrels for the beds.

assuming i am able to get a 8 foot hot tub, i read they hold 400-500gallons, how many GB could that support do you figure?

I think I found out why they dont get used often, it seems they are just so heavy. up to around 1000 pounds. and that is DRY!

the growbeds will actually warm your water on those hot days.. unless you do a constant flood type system

if your ft is 400 gallons, you could support 800gal of gb (2:1) but you'd need a sump or an indexing valve.. having a sump and increasing the volume of water would help in slowing temp swings

it might be easiest to start with something else (like bluegill, very hearty and will grow if fed a good feed) and monitor your wanter temp's through the year.. you might be able to run 2 "seasons" of fish, trout through the winter and something else in the summer..or if water temps are stable and low enough to grow trout you'll know

you could also check with pond owners in your area to see if anyone is doing trout year round, or seasonally

i plan on trout in cool months only. cooling water is a costly task, and we get cool weather long enough to feed out a crop of fast growing rainbows. your question was "on the cheap"
i just can't see the cost of geothermal as being cheap.

What you are talking about is very common with geothermal heat pump systems, and is a cost effective solution for small land areas. The problem with verticle loops is the expense of drilling the well. It is generally (though not always) cheaper to excavate the land and lay horizontal loops and then backfill the hole.

Ok man just saw this topic and thought I'd give what info I have from my system. I have a 220gallon reservoir . I ran tubing out of it about 5 ft to the ground, continued on about 5ft into the ground with 5 coils under the dirt then back up to the tank with the return side insulated. It's powered with a 350gph pump. What I've seen with my system is most of the time when the external temp rises from 95 degrees to 115 degrees it's doesn't show much efficiency.However before geothermal my res temps would hold the temp it had during the day all night( assuming tank volume the cause),.. After the geothermal my res drops 1.5 degrees if my water temp is between 78-79 degrees at night. Once it was on and running a few days , as the res temp dropped so did my cooling efficiency. My system seems to maintain its temp now through the day(73 degrees) and cool down (70 degrees) more at night than it did before geothermal. So my suggestion is get a big enough reservoir to help control the temp fluctuations, get the original water temp where you want it, run at least the amount of pipe and depth I did and get a 500 gph pump and see if it will maintain your original temp through the hot days.

I geuss I should add that the system in high temperatures seems to act more like a temp buffer to slow the reservoir temp from rising as fast. Here it's been about a week to start working, then when I get the temp of the reservoir around 70 and let it run it takes like a weekand3 days for it to get up to 75degrees in above 90 to 115 degree days. With that being said if I get 2or3 days of cool or rainy nights, it has dropped to 73 on its own with just my fan on over the plants. So it's more like a inground temperature delay system than geothermal cooling