Backyard Aquaponics
A place to discuss aquaponics

I live in middle TN and I"m going to attempt a rainbow trout based system. The main problem in middle TN is the HOT summers so here goes.

My fish tank plan:
2x4 walls lag-bolted to 4x4 corners insulated with 3.5" of foam. ID of tank approximately 72"L x 30"W x 36"H for about 330 gallons.

My sump tank plan:
about 6 "blue barrels" linked and buried about 1-2 feet for a "geothermal" effect.

Grow bed plans:
space available: about 20'x4' so I was thinking of using 4 - 4'x3'x1' grow beds.

questions:
How do I link the GB to the ST system while keeping the geothermal aspects to cool the water?

How should I attach the ST to the FT?

All suggestion and input is welcome

Welcome ocelott, keeping trout through summer is not an easy task.

Here is a member that has achieved it viewtopic.php?f=18&t=9917&hilit=chilly

I don't have access to chest freezers, but I love the concept.

I may be able to use the idea for the sump tank...I've seen on another site a way to use the chest freezers as hyper-efficient chest refrigerators by wiring in an electronic controlled thermostat into the controls

Hmm...burying a few chest "fridges" for the sump may work - but more energy = more cost...

Yea thats the issue, heating and cooling comes at a cost. Most of us stock according to season for this reason. The temp losses/gains through the GB's etc play a big part in controlling your FT temps obviously.

This issue has been extensively debated throughout all AP forums over the years and there is no easy, cost effective solution as yet.

Good luck

The problem with Tennessee weather is the HUGE temperature variable...it can get to 100F+ (38-39C) in the summer to 25F (-4C) in the winter. It makes for a challenge for ANY fish and plant.

In my current location I do not have access to a greenhouse ATM - I may build a lean-to greenhouse over the grow beds for the winter and focus on cold weather plants - kale, spinach, and other hardy greens in the winter. For the spring/summer/fall: toms, peppers, onions, etc.

I do not have any background in thermodynamics but I was thinking that 3.5" (9cm) of insulation - I have an alternate plan that can increase the insulation to 5" (12.7cm) - should be enough to maintain tank temps below 75F (24C) - if I can keep the sump tanks below 70F (21C)

I feel that if the sump tanks are over 70F then keeping the tank at a fish safe level will be a problem

Any thoughts?

Yea our weather here in Oz is similar, particularly where I am, really hot summers and really cold winters.

Most of us here are able to have Silver Perch all year round although they only mostly feed and grow during the warmer months. October through to April -ish.

And the cooler months (April - Oct) is trout season. The good thing about trout is we can get them to plate size in those months so no real need to take them any further is my opinion. Im not fussed on growing record size trout.

And there are a few other species that fit into the warmer climate catagory. I believe over your way you have the talapia and bluegill etc

I suppose its up to you how far you want to go with preparing your system to either heat or cool. I have not done either so Im no real assistance sorry. I just run my stock as per the above.

To start with, I love the idea of using constant ground temperature to warm/cool water for an AP system, but unfortunately, burying a few barrels just below the surface is not going to cut it. You need to be excavating in the order of 30-50 feet to start finding constant temperatures, dependent on location and soil composition. I looked at doing some thing like this years ago and found this paper useful for the temperature modeling: http://soilphysics.okstate.edu/software/SoilTemperature/document.pdf. I also tripped over this paper on borehole geothermal design for home heating/cooling which also contains some good information: http://ktisis.cut.ac.cy/bitstream/10488/870/1/C55-PRT020-SET3.pdf. There is also lots more out there on the interweb which will tell you that you need to keep digging!!

When it comes to insulating tanks, that modeling is a lot easier but I think you'd better get the system design premise right first.


Scott

In Tennessee, perch are not on the approved list - unless I can get the blessing of the State. My other options are Cats, Blue Gill, or Tilapia - as far a good eating fish. It gets far too cold for Tilapia and Blue Gill so my options are Cats and Trout. I much prefer the taste of Trout to Cats.

I think that it will be worth the effort in preparation if it works. If it doesn't work - there is always the cats.

I may have to dig a test hole and measure the temp at varying depths during day and night- at 6" intervals to see where the ground temp is in my area. I'm in full summer here so that should help determine my tank depth.

I'm sure you local water authority already has that information for your area?

Thanks for those links - they were very interesting. Thank goodness I've got heavy clay soil - that should help with minimizing the depth required for the sump.

So it sounds like I've got a bit of good old fashion testing to do - i.e. I may have bit off more that I can chew.

1- check temperatures of the soil at varying depths - both day and night
2- set up a sample tank with 3.5" insulation to test water temperature
3- set up a tank with 5" insulation to test water temperature

should I scale the insulation thickness in relation to volume of the tank? i.e. 1/2 scale = 1/2 insulation thickness?

I may have to bury a blue barrel filled with water and a "breather-tube" so I can test the temperature with the barrel buried four feet deep - with the top of the barrel two feet below ground level. since I work noon to MN that should allow me to check the temp in the morning and late at night

yep - I've got the PDF for the
"RULES OF THE TENNESSEE WILDLIFE RESOURCES AGENCY"
on my desktop - which is where I got the fish info from.

As far as the temperatures for fish goes that came from research on the internet

I looked into trying to do something similar a while ago and gave up on the idea, mostly because I learned that anything I run underground, unless I go to ridiculous depths, is pretty much just going to (eventually) warm up the surrounding ground area and negate any initial cooling effect it had.. It would meet somewhere in the middle but that would still be too warm to justify the effort..

I decided to try to get some trout through winter and I might try to keep a handful in an isolated/insulated tank in the shed that has filters but no growbeds, and swap out some water between its sump and the outside systems sump in the early hours when it's coolest..