ICP Test Results w/ Tin Mystery

[JJKK]

Got my ICP test results today and nothing too concerning except for my salinity was not at 1.026 as my Milwaukee monitor was telling me but at 1.023. That is an easy fix.

The one that I am trying to figure out is Tin. In my RODI water, in measured 148.9 µg/l. In the tank water, the result was 20.11 µg/l. So, I need to go figure the source of Tin in my RODI container(55 gal food grade white plastic container). I have a float valve there as well as a magnetic sensor to let the APEX know if I have low water amount in the RODI container. But can anyone tell me how Tin could get reduced by about 130 µg/l in the display tank? What could be absorbing it and do I need to address it for the display tank or if I get rid of it in the RODI, it should be back to normal?

Thanks for any insights.

 

[Spare time]

Tin, from my understanding, can come from glass and new pvc pipes. As for how it was reduced, I am not sure. Maybe it is only recent (such as your TDS going up from needing new DI resin) and that it never went down.

 

[Randy Holmes-Farley]

Tin can be in many forms and without knowing the form, it is impossible to say where exactly it went, but it could simply be precipitating or binding to surfaces, including organism membranes, rocks and sand, GAC, etc.

 

[JJKK]

Checked the float inside the RODI container and it was fine. Also inspected the OS-1 optical sensor and the magnet that I used to positioned it inside the RODI container and it had no corrosion as well.

I am thinking the next step is to do an ICP test for the RODI water right before it enters the RODI container. I have yet to change the membrane on my Spectrapure RODI unit ever and its been 3.5+ years. I get 0 measured TDS water out from it so never found the need to. Could it be the culprit?

Anyone know if I can just do an ICP test on just the RODI sample at a lower cost?

 

[Randy Holmes-Farley]

IMO, it is very unlikely tin is coming out of the RO/DI in significant amounts if the RO membrane is intact and the DI is not depleted (meaning 0 ppm TDS).

 

[JJKK]

IMO, it is very unlikely tin is coming out of the RO/DI in significant amounts if the RO membrane is intact and the DI is not depleted (meaning 0 ppm TDS).

Just got my RODI test samples back yesterday. Do note that ATI-ICP was nice enough to allow me to send in 4 separate RODI samples with just one of their test kit that has 1 vial for RODI and 3 for display water. I saved some money by not having to buy 4 separate test kits(though I could have gotten away with 3 separate RODI tests).

Here are the 4 RODI samples I sent in and the link to their results:
RODI water in the RODI container. RODI unit with the RODI booster emptying in the 55G food grade container with a plastic float valve. This is a repeat of my previous test just to make sure that it was not a fluke: https://lab.atiaquaristik.com/publicAnalysis/98107
RODI water directly out of the RODI unit with use of a RODI booster: https://lab.atiaquaristik.com/publicAnalysis/99154
RODI water directly out of the RODI unit without a RODI booster: https://lab.atiaquaristik.com/publicAnalysis/99155
RODI water directly out of the RODI unit without a RODI booster and after changing out both membranes: https://lab.atiaquaristik.com/publicAnalysis/99156

The result clearly shows that RODI water that touched the RODI booster registered Tin amounts. I am working with the RODI booster manufacturer to get a replacement and sending mine back for them to replicate my results.

 

[Randy Holmes-Farley]

Doesn't it seem like the RO/DI container is adding the majority of the tin? It has a hundred times as much as directly out of the RO/DI?

 

[JJKK]

So my theory about the high amount of Tin in the RO/DI container is that it is the result of accumulation over the course of over 11 months(I installed the RODI booster in Jan 2020) from the RO/DI booster output that contains Tin. Let me know if that is a wrong way of thinking about that.

Couple with the fact that with the RO/DI booster in the water stream, I was still getting Tin output and removing it off-line, resulted in zero level of Tin, is there another logical conclusion I should consider other than the RO/DI booster is the source of my Tin problem?

Thanks for your help Randy.

 

[Randy Holmes-Farley]

So my theory about the high amount of Tin in the RO/DI container is that it is the result of accumulation over the course of over 11 months(I installed the RODI booster in Jan 2020) from the RO/DI booster output that contains Tin. Let me know if that is a wrong way of thinking about that.

Couple with the fact that with the RO/DI booster in the water stream, I was still getting Tin output and removing it off-line, resulted in zero level of Tin, is there another logical conclusion I should consider other than the RO/DI booster is the source of my Tin problem?

Thanks for your help Randy.

I don't see how it accumulates there.

It might bind to the sides or settle out as a precipitate, but that process doesn't suddenly raise the level in the water unless you stir up precipitate or scrape the sides.

It certainly seems bad for the booster, but I am not really understanding how tin gets through a functioning RO/DI when NOTHING else apparently did, even things that ought to be present at much, much higher concentration in the starting water coming from the booster (such as sodium). Maybe the method is not set up properly for low concentrations of sodium???

What did you collect it in for "RODI water directly out of the RODI unit with use of a RODI booster:". I'm concerned that it may have come post DI.

And finally, maybe the tin value for the ""RODI water directly out of the RODI unit with use of a RODI booster:" is not accurate.

It just seems exceptionally unusual to me for tin to be present in that fluid when nothing else is.

 

[JJKK]

I was holding off on adding anymore RO/DI water to the container till I got the ICP results back. So, I probably extracted the RO/DI sample from the container, when it was pretty low. And the hose I use would have been laying on the bottom of the container where Tin precipitant may have accumulated.

"RODI water directly out of the RODI unit with use of a RODI booster:" - that water sample would have come out after the DI filter. What is this implication?

Do you think my best next course of action should be to send out samples to another ICP tester?

 

[Randy Holmes-Farley]

I'm not sure of what is the best step.

Are you sure you need a booster?

It seems you need a new storage system anyway. Or at least to carefully clean what you have and assess whether the float switch might be part of the issue.