ICP-OES shows chromium. Now what?

BatmanGefle · Nov 7, 2016

Hi,
my first Triton-test came this week and is surprisingly good, except it shows 3.11ppb chromium.
Info on chromium in reef tanks are very scarce (or my Google-magic is bad, anyway I can't really find some useful info). Elevated levels seems to disturb metabolism and branching in coral skeletons, but that's pretty much what I can find.

Is 3.11ppb really something to worry about? It's enough to be red-flagged by Triton but do I need to make an effort to remove it?
And if so, how?

As far as I can tell my corals (lps and some easier sps), fish and inverts are fine so there's no imitate danger, but I'm new to this so I'm having some difficulties knowing what to look for except obvious things...
Thanks//Martin

Randy Holmes-Farley · Nov 7, 2016

I don't know, but I'd doubt it is a serious problem. The natural level is about 10 x lower.

Any metal parts in the water, such as hose clamps?

BatmanGefle · Nov 7, 2016

I'm not really sure where it's coming from. My clamps are all plastic but it might be from the metal brush I used to clean the rock with. A few strands might have come of and lodged in the rock without me noticing...but shouldn't iron and such also show up on the test if the cause is something metallic in the water (the only high numbers I have is a few ppb Cu and some Li and Ba, everything else is spot on or slightly low)?

BatmanGefle · Nov 7, 2016

But something just occurred to me...I have pierced the water pipe to connect my RO-unit (pre-filter, carbonfilter, RO-membrane and last an ion-exchange media). The water pipe is chromed on the outside... Can some chromium have passed through?

Randy Holmes-Farley · Nov 7, 2016

BatmanGefle said:
But something just occurred to me...I have pierced the water pipe to connect my RO-unit (pre-filter, carbonfilter, RO-membrane and last an ion-exchange media). The water pipe is chromed on the outside... Can some chromium have passed through?

Chromium should not get through an RO/DI.

BatmanGefle · Nov 7, 2016

Ok, thanks.
I´ll see if I can find the source, but other than that I´ll just wait and see what the next test shows.

Randy Holmes-Farley · Nov 7, 2016

If you are concerned enough, something like TLF Metasorb or a Polyfilter may help.

BatmanGefle · Nov 7, 2016

Metasorb don't absorb chromium according to the text on the back of the package.
Polyfilter - not sure, can't find anything other than 'removes heavy metals' but it doesn't specify more than that.

Randy Holmes-Farley · Nov 7, 2016

BatmanGefle said:
Metasorb don't absorb chromium according to the text on the back of the package.
Polyfilter - not sure, can't find anything other than 'removes heavy metals' but it doesn't specify more than that.

That will depend on the form of chromium present, and how it may be bound to organics as well. Many of these sorts of companies have freshwater data and may not correctly extrapolate to seawater. Selenium is claimed to bind for example , and yet it is in a likely form (SeO4--) that is very similar to chromium in seawater (CrO4--).

BatmanGefle · Nov 7, 2016

Ok. So it's a hit or miss, but worth a shot then.
I still think I'll wait and see what the next test shows. I can't find anything that seems to indicate that high Cr is dangerous in short terms (that I have to deal with it right away) even though it seems rare to have elevated levels.

jason2459 · Nov 7, 2016

I personally wouldn't do anything drastic unless you keep showing chromium or other trace metals that could interfere with each other.

I would probably do a quick look around for corroding metals in and around the tank.

BatmanGefle · Nov 7, 2016

jason2459 said:
I personally wouldn't do anything drastic unless you keep showing chromium or other trace metals that could interfere with each other.

I would probably do a quick look around for corroding metals in and around the tank.

That's pretty much what I plan to do for now, since there seems to be no immediate danger... All pumps are brand new (six months old Ecotech, that shouldn't have started to corrode) but my UV-C is connected to an old Jebao, I'll open it up and see when I get home (I work away from home and got the results while I was away so I haven't had a chance to do it)...
Hose clamps should also be all plastic, but I'll take a look at them as well, in case an odd one has slipped through...
But again, shouldn't the test show other metals as well if there was some metal in the tank that causes it?