# [Wet Thumb Forum]-aluminium toxic ?



## perrush (Feb 24, 2003)

Hi,

In my region almost every one says Al, used in DIY lighthoods, will poison the water with Al (Al2O3 ??).

I'm willing to believe everthing one says, but only if I'm convinced myself









So I went through some files and found that :

Al2O3 has an LD50 with rat and mice of more than 5000 mg/kg. That's more than KNO3 which has an LD50 of 3750 mg/kg. Ofcours I know that for aquatic life, other rules can count.

Secondly in my tap water, 200 µg/L Al (0,2 ppm) is allowed to be in the water.

Lastly : isn't AL used in drinking cans, fast food packages end so on ???

So these three idea's let me think Al isn't that toxic. But I've no hard data for aquatic life.

Has anyone any figures how toxic Al is for aquatic live ? Or any experience with Al in DIY lighthoods ?

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## perrush (Feb 24, 2003)

Hi,

In my region almost every one says Al, used in DIY lighthoods, will poison the water with Al (Al2O3 ??).

I'm willing to believe everthing one says, but only if I'm convinced myself









So I went through some files and found that :

Al2O3 has an LD50 with rat and mice of more than 5000 mg/kg. That's more than KNO3 which has an LD50 of 3750 mg/kg. Ofcours I know that for aquatic life, other rules can count.

Secondly in my tap water, 200 µg/L Al (0,2 ppm) is allowed to be in the water.

Lastly : isn't AL used in drinking cans, fast food packages end so on ???

So these three idea's let me think Al isn't that toxic. But I've no hard data for aquatic life.

Has anyone any figures how toxic Al is for aquatic live ? Or any experience with Al in DIY lighthoods ?

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## imported_Xema (Apr 1, 2003)

Hi,

DIY light hoods made aluminium is not toxic for water live, beacause these is not in contact with water.

I have a DIY light hood made aluminiun and there is any problem.








Feel the Chocolate Gourami power
www.aquagarden.net
www.acuariofilia.net


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## perrush (Feb 24, 2003)

@ Xema,

maybe the Al isn't in contact with the water, the vapourized water does condens on the Al-hood and drip into tank again.

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## imported_Xema (Apr 1, 2003)

I protec my AL-hood with a metacrilate film, and I have painted AL-hood with a black spray, which protec AL-hood of the corrosion.

Click here








Feel the Chocolate Gourami power
www.aquagarden.net
www.acuariofilia.net


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## Roger Miller (Jun 19, 2004)

I don't have numbers for you, but my understanding is that aluminum is toxic to both plants and animals. Specifically, I'm talking about the aluminum ion Al+3. Al+3 can be a limiting factor for crop yields in acidic, clay rich soils. But that, as far as I know, is the limit to the problem.

Chemically, aluminum forms an extremely insoluble hydroxide, much like ferric iron. Because of that reaction, the dissolved ion can't reach biologically significant levels unless the pH is very low. 

Al2O3 is definitely not a problem. That is the mineral corundum, which is extremely hard and inert. Under the right conditions it makes the gem stones ruby and sapphire. Aluminum metal is also not a problem, as it becomes quickly coated with a non-reactive skin of hydroxides and oxyhydroxides.


Roger Miller


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## Kevin Jones (Apr 4, 2004)

I was doing a water quality survey this past year for a spring-fed lake whose pH was consistently below 4 and the Al concentrations were through the roof. This was the main attribute for the lake's lack of much of anything living. That sort of problem isnt really and issue until the ph is below 5 if i recall correctly. 

and if you're protecting the hood with paint or sealant, it shouldn't be an issue.


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## perrush (Feb 24, 2003)

@ All :

Tnx for your help.

So let's take the extreme. Even Al IN the water shouldn't be a problem in normal pH ranges (above 6) ??

--
English isn't my native language, but I guess you already noticed that ))
--

Perrush


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## Shane A smith (Jun 15, 2003)

Aluminum is much more toxic in PH under 5.5. so if your around 7.0 even a little aluminum wouldn;t hurt too much.


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## Roger Miller (Jun 19, 2004)

Ksp of Aluminum hydroxide is 2x10^-32. The table below gives the concentration of aluminum in a dilute aqueous solution at 25d C in the presence of aluminum hydroxide.

pH 7 Al+3 0.00000054 mg/l
pH 6 Al+3 0.00054 mg/l
pH 5 Al+3 0.54 mg/l
pH 4 Al+3 540 mg/l

The Al+3 concentration increases by a factor of 1000 for each unit decrease in pH.

Aluminum metal in water is not a risk. If the aluminum reacts with water (that is not a given, because the metal is not very reactive) then it will form the hydroxide. As long as the pH is (as Shane pointed out) about about 5.5 there should be no problem. If aluminum were a problem then aluminum cookware would be unsafe.

The toxicity of metals is usually further reduced when there is bicarbonate (KH) and/or organic compounds in the water. Metals typically form complexes with bicarbonate or organics and that decreases their biological effect.


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## perrush (Feb 24, 2003)

@ Roger & Shane :

tnx, as always to the point info









Did a little research myself :

http://www.dar-tech.com/docs/ON-310MSDS.pdf
states that Al(OH3) has an fish LC50 > 10 g/L !!! and a daphniaa EC50 also > 10 g/L

http://www.cleartech.ca/inside/msds/hal-12-28-2001.pdf
says that the TLm(48 hours, mosquito fish) = 240 mg/L ... also a quit big number.

now finally ?
Will EDTA effect the toxicity of soluble Al ?? As both Fe and Al are 3+, it could well be that EDTA incubates Al too. Making it even less toxic ? Does this makes sence ?

edit :
Did find a source which talks about this.
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v338/n6211/abs/338146a0.html

there they says EDTA would INcrease Al3+ toxicity









--
English isn't my native language, but I guess you already noticed that ))
--

Perrush

[This message was edited by perrush on Sun August 17 2003 at 01:49 AM.]

[This message was edited by perrush on Sun August 17 2003 at 01:50 AM.]


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