Backyard Aquaponics
A place to discuss aquaponics

I live in texas where all but one type of tilapia is illegal. We are required to stock the bread that die at 50 deg F. I have a solar heater which has 25 feet of 3/8 copper brazed to a sheet of roofing copper and enclosed in a glass box. It heats very well when the sun in shining (making steam in full sun light with low water flow). However, I live in East Texas and it is very often cloudy in the winter and solar does not work so well. Spending my money on high electric bills is not really an option either. So this is my solution..

I am a HVAC person by first trade so this is super simple for me. For the rest of you you can either learn the simple skills if you have to tools OR pay a friendly air condition guy a few dollars to do it for you.

The method.
1)Buy a $100 4 or 5 thousand btu window unit.
2)Tap the freon line on the low side and Pump the freon out.
3)Unscrew, unmount and cut free (with a tubing cutter) the back coil off
4)Mount unit near fish tank or outside of the green house. Extend the copper freon lines going from the coil to the unit using 3/8 inch copper, soft plumbing copper is fine.
5)Use appropriate length of 12 inch pvc to make a loose fitting coil from 25 feet of copper tubing.
6)Place and epoxy coil into pvc
7)Wind 50 feet of nylon tube inside the pvc and fill with salt water. Epoxy in place
Fill with salt water, cap and drill small vent hole in top(steam escape)
9)Braze extended lines to coil. Purge or vacuum.
10)Put the freon back into the unit.
11)Hook circulating pump to move water from tank through heat exchanger and back to tank (extra chance to add some more o2)
12)Pull out the control panel
13)Remove and extend the two wires to the thermostat so that you can get the thermostat close enough to the water to allow the thermostat bulb to dangle into the water.
14)Secure all electrical connections to be water tight. (liquid electrical tape)
15)Turn on and adjust thermostat to the desired temp.

*Even simpler use 1/2 flexable stainless steel tubing and place directly into water tank. Browns Gas weld the copper to the stainless or epoxy the lines together.

Power Usage: These units pull very little power and can operate in this heat pump mode just fine; i have done this with my water heater. An emergency shutoff thermostat might be a good idea to prevent accidents if the unit fails to shut off; you know so you cant cook the fish. In mild climates like Texas these work all winter long with no problems of any kind. Only about one or two weeks out of the year so they run a lot. The idea is that you can deliver almost 3 time the energy to the water than you used to pump the freon because the heat is drawn from the environment. Further, if you have a large pond or lake near by(not more than 30 feet or so) you can do away with the fan and place the cold coil in the pond saving another amp of power.

HEALTH: Copper can not be put into the tank so Stainless is required or a heat exchanger.(per post below)

Help If you live within two or three hundred miles of East Texas I would be more than willing to make the conversion for you in exchange for Gas, food, lodging expenses, plus materials.

For those of you who just happen to have a hydro drill. You can stick a hundred feet of 4 inch pipe into the ground and run a 3/4 inch pipe down to the bottom, cap both ends and circulate water through it picking up about 1400 btu of earth heat which will be the yearly average temp in your area. That about 68 or 70 here.

For those who have access to a deep trencher or backhoe: Also you can trench thin-walled 1 1/4 inch pvc 6 feet deep (making a manifold) and collect 14.4 btu per square foot of ground you place the pipes in. (Space the pipes 6 foot apart)

I have used these systems to cool hydroponic nutrient because of our 100 degree F days here. However, they will also work in reverse to heat your fish. I am just starting aquaponics so it will be a while before I can put solid numbers to this.

Hey DDM:

Welcome to the insanity!

I tore apart a dehumidifier to see what kind of heat exchange I could get out of it as an experiment, see here:
http://backyardaquaponics.com/forum/vie ... c&start=45

The downside is that copper is toxic to fish - you would have to coat the coils with something, isolate the tubing with an intermediate tank, or use another material.

Edit: Air conditioners come up on freecycle all the time:
http://www.freecycle.org/

Yeah, that's the first concern I had too, DD. The copper may be a problem. However, that doesn't mean you shouldn't test it and tell us how it goes, Dan! Tilapia are pretty tough, and I think there are test kits for copper in the water. If it is easy to do, go ahead and make one, test the copper in your starting water, then run it for a month. Monitor temperatures and copper levels and see how it goes.

I'll see if I can find some numbers on toxicity levels for copper and fish. I think crustaceans are more sensitive.

Collected Pieces:

http://www.epa.gov/R5Super/ecology/html ... les.htm#cu

Effects on aquatic organisms: Copper sulfate is highly toxic to fish [28]. Even at recommended rates of application, this material may be poisonous to trout and other fish, especially in soft or acid waters. Its toxicity to fish generally decreases as water hardness increases. Fish eggs are more resistant than young fish fry to the toxic effects of copper sulfate [26]. Copper sulfate is toxic to aquatic invertebrates, such as crab, shrimp, and oysters. The 96-hour LC50 of copper sulfate to pond snails is 0.39 mg/L at 20 C. Higher concentrations of the material caused some behavioral changes, such as secretion of mucous, and discharge of eggs and embryos [8].

A Medication:
Copper Sulfate Pentahydrate
USE: Algaecide, anti-bacterial, anti-fungal, anti-protozoan. Treats, ich, oodinium, sliminess of the skin, flukes, crustacea (argulus).
DOSAGE: 1 drop per gallon of aquarium water = 0.15ppm. To make stock solution: Use 21 grams to one pint of distilled water. Never use copper when water hardness is less than 50ppm. Optimum is 200ppm.

Article on Gill Damage in Tilapia after short term copper exposure:
here

OK, that's enough for now. I guess it all comes down to how stable solid copper tubing is when exposed to water. (Remembering that your pH may be above or below neutral, too.)

Edited to fix the URL link

It would not be hard to make a brime heat exchanger. That is use are large plastic container like a three foot (1 meter) section of 12 inch pvc with caps. Install the copper coil and a much longer coil of nylon tube and fill with salt water. I think that seem like the best option. I do not want metal in the fish I eat. Thanks for the info. That will save me some trouble!

I just need to find out what the heat transfer rate of nylon tubing is so I can match it to the btu output of the unit to find the length needed to remove the heat.

Its quite a change to move from simple hydroponics to aquaponics. However, with some duck weed I hope to eliminate the need to buy chemicals.

You'll probably still need to buy de-chlorinator unless your water is untreated well water.

I don't quite understand the description of a brine heat exchanger. We do like sketches and pictures. (Hint hint!!)

oooooo...you editted the first post to take the copper problems into consideration?!? Alright, I wasn't confused for too long.

At any rate, we still like sketches and pictures.

Ok I will take the top off one of my small versions and take a picture. I think the stainless steel tubing is the better option though.

JP, I haven't been using dechlorinator all this time - I called our water dept and we only have chlorine, so the tap water goes into tubs for a few days then I use it.

If it was chloramine then I would have to use chemicals.

Dan nice to see another fellow Texan on the forum. I wasn't born in Texas but I got here as fast as I could. I can't take respnsibility for my parents short comings:). Hey how hard would it be to heat a septic tank with one of your methods if I bury all but 2' of it? I am 30 miles south of Livingston. The reason I am asking is I would rather raise tilapia year around if I can affordably keep my water temp high enough.

So far.

Don't count on them calling you if they decide to go to chloramine one day either.

Wow did I learn about that recently. Short on rain for the first time this year I filled a drum with tap water to top off my systems fish tank and let it sit for a few days. Got some new fish quite sudden like and in a hurry could not find my pond test strips to check the chlorine of that drum full of water. I set up the aquarium filled it with water put in the fish. In a matter of seconds the fish started flashing and running their snouts into the gravel. I knew I had a big problem and it was chloramine. Thank heavens I had bought some ammonia/chlorine/chloramine remover last trip to the LFS. Put in three teaspoons and the fish settled down some. The next day they were just fine.
I don't like to use the stuff (chemicals) but had to be done in this situation.

Yes its good to see another Texan thats into aquaponics! To bad you are so far away.

I guess you could heat a septic tank but you would loose a huge amount of heat. It would be best coated with an inch of polyurethane(not the stuff in the can). Come to find out that metals are used to kill bacteria so it would likely also need stainless tubing in the tank to avoid killing bacteria. I am not so sure copper would kill bacteria. IN A/C systems I see alage and nasty bacteria at work in and around coils, though not directly on the copper. Come to think of it aluminum seems to not affect anything.

If you want to make methane, I dont know how many BTUs of Gas you would get verses the energy input. Besides there are much better ways to get energy from biomass than making methane; but not simpler(methonol, CO, carbon, hydrogen ect).

Welcome to the AP insanity DDM, I've ahead of some as I have a couple of lengths of S/S tubing....just need the rest of the stuff now


Love the carrot

I thought cooking in aluminum was linked to Alzheimer's.....hmmm...can't remember.