I've googled this a fair amount and there are a number of threads where peoples' ICP tests show high levels of Chromium, but none of them have a solid answer. I'd like to aggregate what I learned and get feedback as to whether my conclusions are solid or whether I am missing something.
FWIW -- I am dosing using the Triton Method. That's the only thing that changed since my first water test. It would be ironic if that's where the Chromium came from!
- There is little evidence of high chromium causing issues with reef aquariums. I saw a reference to a study on (if I remember correctly) fish organs being affected. But that was it except for the ICP tests warning that it was higher than usual. I believe this thread discussed that people used to dose it in the hopes of getting better color, but now I can't find it.
- Triton ICP tests apparently will indicate that high Phosphates may throw this off. I didn't have a Triton test or see the original information, but it wasn't clear how high would throw it off. Mine is fairly low, so not too concerned. But I list it here for reference.
- @Randy Holmes-Farley posted a very interesting link in one of the threads that measured the Chromium concentration in a number of commercial salts. All of them look like they were high enough for the Triton test to scold you over it! If this is still accurate (the article is older) then the high levels make a lot of sense. (http://web.archive.org/web/20001215...om/fish2/aqfm/1999/mar/features/1/default.asp)
- A number of the posters searched madly (occasionally blaming OCD) for a piece of metal that was causing the high levels. Some found something, but removing it only sometimes seemed to solve it. It seems clear that Chromium could enter the water this way, but I was not encouraged by the success rate.
- My own level of 0.01ppm seems not too bad, but I'll see if it keeps going up (or disappears) in a couple months.
- The next time I do an ICP, instead of having my RO tested too I am going to test freshly mixed salt. Unless I totally forget I'll paste it here sometime after the new year.
FWIW -- I am dosing using the Triton Method. That's the only thing that changed since my first water test. It would be ironic if that's where the Chromium came from!