Arsenic…

[reefiniteasy]

Got my latest icp results back from Reef Labs. What are some possible sources of arsenic, if we assume it isn’t test error.

 

[Garf]

Well, it’s only double “optimal”, whatever that means

 

[DaJMasta]

You're talking about 10 parts per billion - the equivalent 10 miligrams in total in a 1000L (260G) aquarium, and if it's ICP OES testing, you probably don't have reliable reading at that level - that could easily be two least significant digits at highest resolution.

FWIW, in a different ICP test service, the threshold for alarm is set at 10ppb rather than 5ppb, and it seems like the ocean average is somewhere around 1.7ppb (ug/L).

I wouldn't worry about it unless it was more elevated, but if you have another test down the line and it increases again, maybe it's worth searching for.

 

[reefiniteasy]

You're talking about 10 parts per billion - the equivalent 10 miligrams in total in a 1000L (260G) aquarium, and if it's ICP OES testing, you probably don't have reliable reading at that level - that could easily be two least significant digits at highest resolution.

FWIW, in a different ICP test service, the threshold for alarm is set at 10ppb rather than 5ppb, and it seems like the ocean average is somewhere around 1.7ppb (ug/L).

I wouldn't worry about it unless it was more elevated, but if you have another test down the line and it increases again, maybe it's worth searching for.

The truth is I could care less. The tank looks spectacular and things are growing. I am waiting for mass-spec results from ICP-Analysis so I’ll post that when it arrives. Just curious is all. I did switch salts since the last icp but I can’t imagine that’s the source.

 

[Dan_P]

Got my latest icp results back from Reef Labs. What are some possible sources of arsenic, if we assume it isn’t test error.

For ICP tests, assume it is noisy data and ignore. Retest if you are worried.

 

[reefiniteasy]

Here are the results from ICP-Analysis.

 

[Randy Holmes-Farley Verified Community Expert]

I have no reason to believe it is accurate, or a problem if it is. The 0.188 ug/L is well below any tox criteria that scientists set. The 10 ug/l from the first one is not necessarily below it.

You can read a lengthy discussion of allowable arsenic levels here:

Prescribing sea water quality criteria for arsenic, cadmium and lead through species sensitivity distribution

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium…

www.sciencedirect.com

 

[reefiniteasy]

I have no reason to believe it is accurate, or a problem if it is. The 0.188 ug/L is well below any tox criteria that scientists set. The 10 ug/l from the first one is not necessarily below it.

You can read a lengthy discussion of allowable arsenic levels here:

Prescribing sea water quality criteria for arsenic, cadmium and lead through species sensitivity distribution

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium…

www.sciencedirect.com

Thank you for the article, I’ll check it out. Where would arsenic in the aquarium come from?

 

[Seymo44]

Arsenic is or was used in pressure treaded lumber. It’s also found in old school flea dips for dogs. Other than that, it’s pretty much been illegal for use in household products since the 70s.

Like previously mentioned, it may just be a test error.

 

[Randy Holmes-Farley Verified Community Expert]

Where would arsenic in the aquarium come from?

Salt mixes, contaminants in anything else you dose or feed, even tap water (big issue in many areas when considered for human consumption). Not really sure since it is rarely an issue that I have seen.