# Aluminium



## LTJ (Oct 15, 2006)

I would like to try out a cooling system for my tank, the apparatus i would like to use is constructed of aluminium. The tank water will flow through heat dissipating ally. sections.

I want to know if the waters flow, and therefore, contact with the metal will result in a significant amount of aluminium contamination.


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## bijoon (Nov 20, 2006)

Is it a liquid cooling system from a computer by any chance?


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## John N. (Dec 11, 2005)

Hmm. I'm picturing water pooring out into an alluminum type "gutter" with the goal of heat dispersion from the water as it travels through this system reacting with the cool air. Correct?

It depends on the quality of the alluminum if it's going to cause any contaimination or not. Since soda cans are made of alluminum, I'm sure there won't be a problem with alluminum degrading the water quality.

-John N.


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## LTJ (Oct 15, 2006)

bijoon said:


> Is it a liquid cooling system from a computer by any chance?


yes it is this one...
Alphacool Cape CORA 442 Passive cooling kit midi in silver |Specialtech.co.uk -
...i figured that it could be fitted in-line with the return of my canister filter, i fancied trying it out so long as the aluminium would'nt cause a problem. John, you mention soda cans but i am sure these are treated or coated with something on the inside?

i am no expert, just thought this might be a good idea as it seems relatively cheap to purchase, easy to fit, and free to run!


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## John N. (Dec 11, 2005)

Ah you're right. My mistake. Interesting system, I've never seen that before.

-John N.


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## LTJ (Oct 15, 2006)

do you think the aluminium would be a problem? I am willing to invest the money in one just to see if it is a workable idea, but not if is going to poison my fish or plants.


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## jamesB (Aug 31, 2006)

Do you use aluminum cookware?

There are really two schools of thought on whether or not aluminum is safe for use as cookware. These two different schools would also argue about whether or not it would be safe to use aluminum piping in your aquarium. The argument basically comes down to whether or not you believe that the passivation of aluminum is sufficient to keep the aluminum from leaching into the environment.
Take a look at Passivation on wikipedia. Take a look at this aluminium oxide note to see why many people believe aluminum should be safe for use as cookware and in an aquarium.

Considering the downside of getting this wrong, the death of your tank inhabitants, you will have to decide the safety issues for yourself.


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## LTJ (Oct 15, 2006)

Thanks for the info James, i am now reasonably assured that this might be a 'safe' idea to try out


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## jamesB (Aug 31, 2006)

If you do give this a try please let us know how it works out. For better or worse, a DIY thread would be great. If you have already started a DIY thread and I missed it, sorry. Work and life some time get in the way.


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## LTJ (Oct 15, 2006)

I will certainly include any progress i make with this idea, i am just looking around for more info re:aluminium toxicity until i commit any money to this. thanks for your help james


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## hoppycalif (Apr 7, 2005)

Bear in mind that you can't get something for nothing in thermodynamics. If you get signifcant cooling you will also get significant pressure drop across the cooler. A filter return is very sensitive to back pressure, so adding devices such as this always reduces the filter return flow, even if only slightly. I'm just saying it isn't a freebie. Also, the heat being removed has to go somewhere, so if this is mounted under the tank, in the cabinet, you will need a fan or similar device to remove the heat from that enclosed area. Any cooler is also a heater.


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## boink (Nov 29, 2006)

why not go to an auto place and pick up a small copper radiator. copper should cool better than aluminum, the only problem being that you are going to have to isolate it from your tank...or aluminum radiator with copper fins


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## blacksmith37 (Oct 10, 2006)

Aluminum (aluminium in UK) is non toxic in any rational concentrations ( remember; water is poison in high concentrations, as some dimwit recently demonstrated.) In the intended electronic equipment applications the fins are mostly for esthetics. In the power transformers on the neighborhood electric power poles the fins are more functional because of a greater heat flux.
I think you could get very limited cooling for an aquarium with thes units. If you could locate a retail source for plain Al tubing it might be cost effective. The alloys you want are 3003 or 3004 , with cladding (pure Al) if available. 
Finned Al tubing are fairly common in chemical plants and power plants; might be a possible source.


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## BryceM (Nov 6, 2005)

FYI this thread was moved from the "Science of Fertilizing" section here to the "DIY" section.


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## littleguy (Jan 6, 2005)

LTJ said:


> do you think the aluminium would be a problem? I am willing to invest the money in one just to see if it is a workable idea, but not if is going to poison my fish or plants.


Aluminum is not a problem. Follow this line of reasoning:
In freshwater, aluminum dissolves only under highly acidic conditions.
Aluminum soda cans are not treated with any special liner as you asked earlier.
Soda is _far _more acidic than aquarium water.
Aluminum poisoning is not a problem with soda cans.
Therefore aluminum poisoning should definitely not be a problem with your proposed idea.
Furthermore, even if aluminum were to somehow get into your tank (and that's a big IF), many factors would eliminate its toxicity naturally:
Most plants cannot help but take up metals in their tissues when they grow.
Dissolved organic compounds in the water will bind with heavy metals and detoxify their effect.
Most tap water conditioners/dechlorinators also bind or chelate heavy metals, with the same result.
For more info on these processes see Diana Walstad's book _Ecology of the Planted Aquarium._

JamesB's links about passivation also are great info on why soda cans and cookware are safe to use.

So my answer is an unequivocal YES IT'S SAFE.



boink said:


> copper should cool better than aluminum


Actually, for practical purposes, both are exceptional conductors. It's like debating between a Porsche and Ferrari when all you need to do is commute to work.  Either material is plenty good.



hoppycalif said:


> ...so adding devices such as this always reduces the filter return flow, even if only slightly.


Agreed.



hoppycalif said:


> Also, the heat being removed has to go somewhere, so if this is mounted under the tank, in the cabinet, you will need a fan or similar device to remove the heat from that enclosed area. Any cooler is also a heater.


YES! Wherever you put the aluminum heat sink, it should be a cool location, that will tolerate a warm heat sink next to it. Adding airflow as hoppy says might be necessary.

How warm is your tank, and how warm is the surrounding area where you plan on putting the heat sink? I would venture a guess that you'll only be able to bring the tank temperature halfway down to that of the surrounding room (or wherever you put the heatsink).


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## t2000kw (Jul 29, 2006)

I used to work for PPG, a company that has a coatings and resins division. It produces a coating for aluminum soda cans, so yes, aluminum soda cans do have a coating that isolates the aluminum from the acid beverage. You just can't see the coating since it's very thin (to save money).

As for aluminum being a possible problem, Walstad in her book discusses that to some extent since the soil substrate in a natural tank will have some aluminum in it, though it's isolated to some extent by the gravel layer on top of it. Seems that it can be a problem and kill fish in high enough concentrations, and other things are likely to get the blame when it's the aluminum that is the problem. The lower the pH the more likely it is to happen. I would recommend reading her book and find that information. She gets pretty technical about the electron charges in the various ions present in an aquarium, but you can read around the tech stuff.

One thing mentioned in the book is that just because something is safe to drink (or eat) out of, it doesn't mean it's safe for fish. She gives information on various substances that have different toxicity levels for humans and fish. For example, fish can tolerate a higher exposure level to mercury than we can. The opposite is true with copper. So you can't simply assume that if it's safe for you, it's safe for the fish.

Sorry, but I don't have a page number for you. The title of the book is *The ecology of the Planted Aquarium* or something like that, _*by Diana Walstad*_.

You can possibly post something in the El Naturel APC forum and ask about aluminum. She monitors the posts and might answer you. I'm not suggesting that you go with a natural tank, just that the forum might be a source of more information from a marine biologist who knows more than most of us do on these things. You can also send her a private message on this if you wish. She does answer them (she has mine, anyway).

Rather than take a chance with your fish, why not add a coating yourself, like in the soda cans, like some polyurethane, to the exposed surfaces of the aluminum. You might research first to see if polyurethane might be a problem. If so, find another sprayable or paintable coating to use. I believe it's pretty nonreactive.

Or, maybe fabricate something out of stainless steel, perhaps, and not worry about aluminum at all. Stainless is not as haet conductive but should be good enough for most purposes. You can always use more of it to compensate.

Of course, they're not my fish, and you can do what you want. I just thought I'd add my two cents.


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## littleguy (Jan 6, 2005)

t2000kw said:


> ... yes, aluminum soda cans do have a coating that isolates the aluminum from the acid beverage.


Wow, really? Then my materials science prof. in college was wrong.... and I've been wrong all these years. They always said that the natural aluminum oxide coating forms the protective barrier that prevents corrosion.



t2000kw said:


> One thing mentioned in the book is that just because something is safe to drink (or eat) out of, it doesn't mean it's safe for fish. [snip] Sorry, but I don't have a page number for you. The title of the book is *The ecology of the Planted Aquarium* or something like that, _*by Diana Walstad*_.


Doh! Quite right you are.  Great point.

Page 14 of the book discusses aluminum toxicity. She says aluminum is only toxic in an aquarium at extremely acidic pH (<5.5) or alkaline pH (>8.0).


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## furballi (Feb 2, 2007)

The automotive industry has used Al radiators for many years. Yes, they will corrode with time and temperature, hence the use of anti-corrosive additive in antifreeze solution. Stainless steel is more inert, but cost more $ and is not a very good thermal conductor.

A compromise solution is to encapsulate the Al core with glass to prevent corrosion. Glass is a good thermal conductor. The Al core should fit snugly inside the glass bulb to maximize heat transfer by conduction.


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## t2000kw (Jul 29, 2006)

I've found college teachers to be a source of misinformation at times. Some seem to make things up as they go along. PPG made a lot of money on those coatings, and I'm sure they still are. Much research went into making a flavorless coating that kept the aluminum taste ot of the beverage. I don't know if there was a time when the aluminum was not coated. If that's the case, your teacher might have been right many years ago (before 1990 or earlier).

Walstad's comments on aluminum leaching would refer to the soil substrate. I don't know if intentionally passing water over the aluminum metal for cooling purposes would add a lot more or not to the water. I'd be cautious, but it might be safe, I just don't know.

If alkalinity or acidity is the only consideration, then just keeping the water well within the safe range would be enough. That's ""IF" it's the only consideration. There is a barrier that forms between the soil and the gravel that might tend to keep aluminum in the soil. And the soil itself forms a barrier. You can look at the sides of some of our tanks and see DRY soil. The water penetrates only partway into the soil. It surprised me!

Anyway, I would be interested in the outcome of this experiment, whether or not the aluminum is coated. Please let us know how this works, if you do it.



littleguy said:


> Wow, really? Then my materials science prof. in college was wrong.... and I've been wrong all these years. They always said that the natural aluminum oxide coating forms the protective barrier that prevents corrosion.
> 
> Doh! Quite right you are.  Great point.
> 
> Page 14 of the book discusses aluminum toxicity. She says aluminum is only toxic in an aquarium at extremely acidic pH (<5.5) or alkaline pH (>8.0).


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## hoppycalif (Apr 7, 2005)

Let's not forget that what we refer to as aluminum is quite often an aluminum alloy. And, those alloys are not generally as resistant to corrosion as pure aluminum is. In fact aircraft aluminum alloys, which are high strength alloys, corrode readily. I have no idea what aluminum or aluminum aloy is used for a heat exchanger.


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## t2000kw (Jul 29, 2006)

Would anodized aluminum be better or worse for this application? Or are there different anodizing metals used for this?


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## littleguy (Jan 6, 2005)

Another good point hoppy. There are all sorts of things that can be alloyed in with aluminum, like vanadium, titanium, magnesium, copper, etc.... If any of those were bad in the aquariums, then all the discussion about aluminum is moot.

Although I think pure aluminum has better conductivity than any aluminum alloy, so the heat sink designers might have made it from plain old aluminum.

Anodizing is a process whereby a thick aluminum oxide film is "grown" directly on the aluminum surface. No additional metals are involved with anodizing. Check here:
Electrochemistry Encyclopedia --- Anodizing

I would imagine anodizing would be preferable for this application to non-anodizing. It should improve corrosion resistance compared to pure aluminum. I think it might reduce conductivity ever so slightly though, probably not a concern for us.


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## schaadrak (Aug 18, 2006)

I don't think you should buy it just because it costs 55£ (a little over $100 US). That's a little bit much for a pipe with some bent aluminum flashing stuck to the outside, and way too much if it kills your fish.

½" pyrex test tubes - $1.00 each
1-½" x 1-7/8" copper flashing - $3.00/ft

So for about $15-$20 and a little imagination you could make essentially the same thing, but have it flow through an known inert material.


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## LTJ (Oct 15, 2006)

Thanks for the information everyone 

I have read Walstads book and it was her comments on aluminium and that it was the metal least readily 'taken up' by plants that stuck in my mind when i started to think about using this as a way of reducing the temps in my tank.

I dont mind spending the money because it would be an interesting experiment, and dare i admit it but i just like spending money on my hobby.

I think as long as there is any doubt over the safety of passing tank water through the aluminium I wont be trying this. If I could afford the space and time to run it on a bare tank I would, just to see how much of a difference it could make, but as long as there is doubt over the toxicity issues I will be looking for other was to combat the summer temperatures.

Thanks again


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## hoppycalif (Apr 7, 2005)

Most house plumbing is now copper. The water lines run from the mains in front of the house up to the shutoff valve are mostly copper too. So, we can't use tap water if we really want to avoid exposure to copper. That tells me that a copper heat exchanger would be acceptable. I don't know how available this would be, but several years ago it was possible to buy copper pipe with fins on the outside, so it probably still is possible.


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## t2000kw (Jul 29, 2006)

Fortunately for most of us our copper pipes have long ago been coated with calcium deposits, isolating the copper from the water. Newer plumbing installations mostly use plastic plumbing. In my older Victorian-era home, I have some copper, some galvanized, and some plastic plumbing. 

If someone does decide to use a copper-based heat exchanger, I would think seriously about how to isolate the copper from the water passing through or over it or get marine life or fish that are tolerant of copper. That would rule out invertebrates, I believe (in saltwater tanks, anyway).


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## hoppycalif (Apr 7, 2005)

In California most, if not all new houses still use copper plumbing. Plastic for water piping was very recently approved, but that only affects the very newest houses. So, I still believe that most of us have tap water that runs thru copper pipes, and that is the primary reason water companies keep the pH of our water above 7. At a pH above 7 copper is almost insoluable in water. Also, most trace mixes, if not all of them, contain a tiny amount of copper. The same is probably true of aluminum, but I haven't specifically checked that.


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## JERP (Feb 4, 2003)

Copper isn't really suitable for CO2 enriched tanks. Bad things happen (the copper dissolves) if you pH is below 7. You won't be able to keep shrimp, and you won't have any problems with snails either.

here's some info I googled:
http://www.plumbingsupply.com/cuinfo.html


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## hoppycalif (Apr 7, 2005)

JERP said:


> Copper isn't really suitable for CO2 enriched tanks. Bad things happen (the copper dissolves) if you pH is below 7. You won't be able to keep shrimp, and you won't have any problems with snails either.
> 
> here's some info I googled:
> http://www.plumbingsupply.com/cuinfo.html


You raised a very good point. I agree, copper isn't for pH below 7.2 or so. And, a cooler would be recirculating tank water, so that is far different from tap water coming one way only.


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## dirtmonkey (Mar 12, 2007)

Aluminum is one of the most abundant elements on the surface of the Earth. 

Element Approximate % by weight 

Oxygen 46.6 
Silicon 27.7 
Aluminum 8.1 
Iron 5.0 
Calcium 3.6 
Sodium 2.8 
Potassium 2.6 
Magnesium 2.1 
All others 1.5 


Whether metallic or oxidized (which happens in a few minutes anyway on an aluminum surface) I seriously doubt Aluminum would be a problem in fresh water. It is less soluble in water than glass. Rubies and Sapphires are aluminum oxide.

Besides, I've used it in aquariums a lot- aluminum screening in terrariums & diy filters, mostly, with no problems. Make sure to ground out any stray voltage if you have it though, I don't know what electrical corrosion could create.


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## Blacksunshine (Aug 11, 2006)

hoppycalif said:


> In California most, if not all new houses still use copper plumbing. Plastic for water piping was very recently approved, but that only affects the very newest houses. So, I still believe that most of us have tap water that runs thru copper pipes, and that is the primary reason water companies keep the pH of our water above 7. At a pH above 7 copper is almost insoluable in water. Also, most trace mixes, if not all of them, contain a tiny amount of copper. The same is probably true of aluminum, but I haven't specifically checked that.


Also keep in mind that most people hit their water with conditioner so the heavy metals are rendered inert. so altho the water may flow thru copper pipes once it reaches your home. the actualy exposure to copper is minimal once its out of the tap. But if a copper item is part of the plumbing of the tank there would be constant exposure and leaching of the copper into the tank. That in addition to the corrosion that copper goes thru def makes in my mind copper a bad element to use for this purpose.

Possibly a cheaper/safer alternative would be to turn one of those cheap mini fridges you can get for 40 - 60 bucks and turning that into a DIY cooler. And just have a coil of vinyl tubing running into and then back out of it. Tho I don't know if that would cool the water too much.









http://cgi.ebay.com/Mini-Fridge-4-L...103514217QQcategoryZ71261QQrdZ1QQcmdZViewItem


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## JG06 (Nov 5, 2006)

How about a used dorm fridge? If you live anywhere near a college or big apartment complex inhabited by young people, you're bound to find a good deal on a little fridge if you wait long enough. 

You could keep your beverages cool and have a soda and watch the fish after tinkering with the aquarium. :idea:


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