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Aluminum piping: is it safe for water circulation in an aquaponics system?  RSS feed

 
Joshua Segatto
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I found the plans to basically create a condenser out of aluminum pipe by running the pipe under ground, then back up and coiled in a 55 gallon drum in order to serve multiple purposes... 1) Draw humidity out of the air and collect the water 2) cool the air to run to a green house 3) cool down the water in the aquaponics system

However I haven't been able to find a ton of information on using aluminum in an aquaponics system other than that it can corrode? Does anyone have any warnings or information on why I shouldn't add about 40 feet of aluminum piping that water would circulate through??
 
Sebastian Köln
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Why aluminium? A (not too thick) plastic (PE or PU) pipe (at least for the underground part) should work just as well, without the risk of corrosion (it's also less expensive). Who knows what happens in the soil…
The next part (the coil) could probably be open water instead of a coil. What matters are temperature and surface area.
 
Bryant RedHawk
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I suspect the plans used aluminum because of its heat sink (heat transference) properties only.

Aluminum not only will corrode in water it will also oxidize and put those new aluminum compounds into the water.
Aluminum, while less expensive than copper has those corrosion and oxidation issues in the presence of H2O, making it not ideal for aquaponics since the aluminum can be fatal to fish, copper can too but it takes a lot longer for that to happen.
Plastics do not transfer heat or cold fast enough to be good for a condenser system, they do work well for most piping setups though.

One other thing about aluminum, it dissolves in the presence of alcohol and should never, ever be used for any part of a distillation apparatus.

Redhawk
 
Joshua Segatto
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Is there a metal that would be safe? While plastic piping would work (I've looked in to using like drip irrigation pipe which is super cheap), as Bryant pointed out, I don't think that the water would cool as quickly as if it were a metal pipe. Additonally, I don't think condensation would happen above ground either by using plastic pipe (point 1 of my original post)
 
Sebastian Köln
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The few millimeters of plastic are not relevant unless there is a good conductor on the other side. And earth isn't really a good thermal conductor. I doubt you would notice the difference. Besides that, you can cover more area with the plastic piping (for the same price).

Edit: A material that does not corrode and is less expensive than copper (which does corrode a bit)…  I don't think stainless steel is less expensive. Glass would be a pain to work with.
 
Bryant RedHawk
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Joshua Segatto wrote:Is there a metal that would be safe? While plastic piping would work (I've looked in to using like drip irrigation pipe which is super cheap), as Bryant pointed out, I don't think that the water would cool as quickly as if it were a metal pipe. Additonally, I don't think condensation would happen above ground either by using plastic pipe (point 1 of my original post)


The plumbing code is pretty much set on copper as the safe drinking water metal pipe carrier.

As long as you aren't trying to get a lot of condensation, then pex will work for most of your piping needs.
I have friends in Australia and NZ that do aquaponics setups with pex but they use "waterfall" coolers to bring water temps down.
 
Roy Hinkley
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What you want is the pipe used for baseboard hot water heating. It's copper pipe with aluminum fins pressed on for maximum heat transfer to air.
Here is a listing on ebay- http://www.ebay.ca/itm/Slant-Fin-Fine-Line-Hydronic-BaseBoard-30-5-Fully-Assembled-Enclosure-Element-/322357925230?hash=item4b0e07956e:g:zT0AAOSwo4pYTzO1

Search for Hydronic Baseboard Pipe or something like that on Amazon or ebay.
 
Joshua Segatto
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According to everywhere I read... Copper piping is a huge no no in Aquaponics due to it poisoning the fish and because aquaponics water is acidic and will corrode it as well... so that's not an option. But from what some of you are saying, Aluminum is just as bad... I'll have to figure something else out. Thanks for the replies! =)
 
David Croucher
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Joshua Segatto wrote:According to everywhere I read... Copper piping is a huge no no in Aquaponics due to it poisoning the fish and because aquaponics water is acidic and will corrode it as well... so that's not an option.


With all metals, acidity is the problem.  Neutral water will dissolve a little metal anyway, but acidified water (rainwater - carbonic acid; surface/groundwater - plant acids; for example) will increase the per mil of metal in the water.  These are often called often called 'soft water'.  Copper is the least problematic pipe metal, lead the worst.  Stainless steel (usually with nickel) is less good than cast iron or rolled steel.  But in all these cases, the best help is to remove the acid.  Naturally, this happens in water from limestone rocks, where calcium and magnesium increase the pH, lime coats the pipe inside and metal take-up is minimal.  Do it yourself?  Add soil-conditioner slaked lime in small amounts to the water - most any farmer will have some.  Or throw some old mortar or concrete chunks into the tank.
 
Joshua Segatto
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David Croucher wrote:Naturally, this happens in water from limestone rocks, where calcium and magnesium increase the pH, lime coats the pipe inside and metal take-up is minimal.  Do it yourself?  Add soil-conditioner slaked lime in small amounts to the water - most any farmer will have some.  Or throw some old mortar or concrete chunks into the tank.


Isn't limestone / concrete also a no no in aquaponics due to the effect it has on imbalancing the PH?
 
Jim Fry
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I have no idea if this is true history/science, but it makes a good story. At one time aluminum was very valuable. It's was just so hard to mine and extract. But it was finally figured out and aluminum became a very cheap and widely used metal. Some folks believe it helped win the war against the National SOCIALIST German Workers Party (the scum nazi's) because the factories of our great American Republic were able to produce so many aircraft and the Allies were able to bomb the socialists into surrender. But, the use of aluminum had become so pervasive during the war effort, that there were great factories left idle after the war. So they (quite naturally) started building peacetime products. And thus everyone starting using aluminum pots and pans for cooking and as dinner ware, and as pizza pans. A couple decades later, Alzheimer's became prevalent. Some folks think there's a connection between "brain disease" and aluminum). I don't know if aluminum is a death metal or not, but I personally will not use it for anything not structural or electrical. Cast iron pans and glass glasses are much better when food and drinking is concerned. I wouldn't use aluminum if you or fish or plants are going to be drinking the water. It's not very permaculture like if you do the cost effective thing, but in the long run poison yourself (or the soil or the animals).
 
Wyatt Bottorff
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Jim Fry wrote:I have no idea if this is true history/science, but it makes a good story. At one time aluminum was very valuable. It's was just so hard to mine and extract. But it was finally figured out and aluminum became a very cheap and widely used metal. Some folks believe it helped win the war against the National SOCIALIST German Workers Party (the scum nazi's) because the factories of our great American Republic were able to produce so many aircraft and the Allies were able to bomb the socialists into surrender. But, the use of aluminum had become so pervasive during the war effort, that there were great factories left idle after the war. So they (quite naturally) started building peacetime products. And thus everyone starting using aluminum pots and pans for cooking and as dinner ware, and as pizza pans. A couple decades later, Alzheimer's became prevalent. Some folks think there's a connection between "brain disease" and aluminum). I don't know if aluminum is a death metal or not, but I personally will not use it for anything not structural or electrical. Cast iron pans and glass glasses are much better when food and drinking is concerned. I wouldn't use aluminum if you or fish or plants are going to be drinking the water. It's not very permaculture like if you do the cost effective thing, but in the long run poison yourself (or the soil or the animals).


There is a lot of evidence for this, as well as poisoning of fish. In every way I view it as a no-go.
 
Jason Learned
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Joshua Segatto wrote:I found the plans to basically create a condenser out of aluminum pipe by running the pipe under ground, then back up and coiled in a 55 gallon drum in order to serve multiple purposes... 1) Draw humidity out of the air and collect the water 2) cool the air to run to a green house 3) cool down the water in the aquaponics system

However I haven't been able to find a ton of information on using aluminum in an aquaponics system other than that it can corrode? Does anyone have any warnings or information on why I shouldn't add about 40 feet of aluminum piping that water would circulate through??


They have a heating pipe system that is a layer of plastic layer of aluminum and another layer of plastic. Called aluminum PEX, I believe, but I used a generic version. I used this in a commercial aquaponics system and had no troubles with it. The metal never contacts the fish water. But I had it full of heating water and the outside was in the fish water, you might have to seal the ends in a way that covers the slight aluminum edge or just use the pipes as a heat exchanger like I did and have the water in the pipes not mix with the water of the system with a small circ pump moving the heat out. The way the fittings are you probably could just put a small amount of silicone on the edge and then crimp it and the fishwater would never get there, however, if you are using the fish water directly you could have clogging issues-- so I'd just keep the water separate, but there are many ways to skin a cat so I'm sure you could if you want to save having another pump.

Good luck,

Jason
 
Gordon Haverland
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Aluminum is corrosion resistant to water near a pH of 7.   For water that has a low pH (acidic) or a high pH (basic), aluminum tends to not be corrosion resistant.  I believe aluminum is present as an interlayer in some kind of PEX.  I believe it is there to stop diffusion of gases, it is not very thick.  Stainless steel would be expected to be corrosion resistant under those kind of conditions, or at least some would be.  I believe some cast irons high in phosphorous would be reasonably corrosion resistant (think of that metal pillar in India).  Is anyone making cast iron pipe out of high phosphorous iron?  You can't forge it, hot work it, or (probably)  weld it.  What a lot of people use, is galvanized iron/steel.  Not that it is corrosion resistant, it is just that the zinc preferentially corrodes until nearly all the zinc is gone, and then the iron corrodes.  Titanium piping would probably work great.    (Zirconium and Hafnium piping too.)    Most of your DWV plastic pipes have a foam core, so they act like an insulated pipe.  There is a way to calculate the critical insulation thickness.  If the wall thickness is less than the critical thickness, then the "foam core" really isn't acting as an insulator.  Concrete is actually pretty good at transferring heat.  Pour a thin layer of concrete.  Lay a serpentine PEX pipe on top of the concrete, pour another layer of concrete on top.  You're probably looking for the thinnest PEX you can make work.  But the concrete should keep the PEX from seeing compressive loads from the soil, the PEX should only have to handle internal pressure loads.  The concrete and the long length of PEX in the concrete is what would help for heat transfer.
 
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