Tin & Aluminum Levels - ICP Testing

[Staggs]

Tin:
Value: 7.17 µg/l
Calculated reference value: 0.49 µg/l

Aluminium:
Value: 21.61 µg/l
Calculated reference value: 0.10 µg/l

I did my last ICP Testing around 1yr ago and my Tin showed 5.21 µg/l and Alumnium was 18.00 µg/l. Other than searching around and looking at all the magnets in my tank (and any other metals) is that number very high or is it somewhat common? Those two did slightly elevate over the year but I'm not sure if that is a lot or not on a 85G display.

 

[Randy Holmes-Farley Verified Community Expert]

I don't think that aluminum value is likely to be a problem based on my testing, but the tin might be and I'd look for sources and/or a way to export it if anything in the tank appears to be suffering.

 

[Larry L]

There's another thread going on discussing low iron glass becoming hazy over time. One of the proposed theories is that the tank was built with the "tin side" of the glass facing in, instead of facing out (see e.g. https://stainedglassexpress.com/blo...academy-finding-the-tin-side-of-window-glass/). I wonder if some of these unexplained ICP reports of elevated tin could be due to that?

 

[Randy Holmes-Farley Verified Community Expert]

There's another thread going on discussing low iron glass becoming hazy over time. One of the proposed theories is that the tank was built with the "tin side" of the glass facing in, instead of facing out (see e.g. https://stainedglassexpress.com/blo...academy-finding-the-tin-side-of-window-glass/). I wonder if some of these unexplained ICP reports of elevated tin could be due to that?

Interesting. That's possible.

I can't at the moment get these papers for free, but they would give an indication of how much tin might be present:

http://www.sciencedirect.com/science/article/pii/0022309375900861

http://www.sciencedirect.com/science/article/pii/S0022309398007996

 

[Randy Holmes-Farley Verified Community Expert]

So I just got access. The calculations below show there is plenty of tin to account for any aquarium value I have seen, but that assumes it comes out, which I do not know. I would expect some small amount to come out and most to not come out from such a thick layer (see below).


In the first paper, the tin concentration is about 1-2% weight % SnO2 for 10 microns. 10 microns = 10 micrometers = 0.01 mm = 0.001 cm

Let's see what that gives us if it all came out!

The density of SiO2 is about 2.65 g/cm3.

So for a 1 cm x 1 cm patch...

1 cm^2 that is 10 microns thick contains = 1 cm^2 x 0.001 cm x 2.65 g/cm^3 = 0.0027 g of material.

That material is ~1.5% SnO2, so that is 4 x 10^-5 g SnO2 in a cm x cm patch

That 4 x 10^-5 g = 0.04 mg SnO2

SnO2 is 79% Sn, so

0.04 mg of SnO2 --> 0.03 mg Sn

That is from each 1 cm x 1 cm patch.

Let's take a 120 gallon tank, with 3 panes 24" x 48" and two panes 24" x 24" = total of 4608 in^2 = 29,729 cm2

If it all came out, thats 0.03 mg/cm2 x 29,729 cm2 = 890 mg of Sn

890 mg tin per 120 gallons (454 L) = 2 ppm

So you could get a whopping 2 ppm tin from typical float glass if all the tin came out.

 

[Staggs]

Thanks for the info, I'm going to go metal hunting this weekend. Everything in the tank looks good and isn't having issues other than the random zoa that is ***** for the day.

If i'm not able to locate the metal (or magnet) would you suggest using the triton detox to get rid of it...and then just observe the level after my next icp test (going to do these probably once a quarter now).