concentration of mag flake and epsom for ICP test

[salty joe]

http://lab.atiaquaristik.com/publicAnalysis/12669

Just when I think things are ironed out, I can't keep snails alive. I have to assume it's the sky high lithium, calling for a total water change and finding the source of lithium.

Besides IO salt, which I don't think was a problem because I had all kinds of live rock critters doing well for months, I suspect Mag Flake and Epsom salt. And maybe kalk slurry, which I no longer dose. Now, I only use clear kalkwasser.

What would be an appropriate concentration of mag flake and Epsom salt for an ICP test?

Also, if I went with food grade mag chloride and mag sulphate, it could still have high lithium and other impurities, right? I can't afford to ICP test every batch. This tank goes through a lot of mag, corraline algae I guess.

 

[Redleg]

Do you have any rare earth magnets in your water. They are a potential source of lithium also.

 

[Randy Holmes-Farley]

In the past, I tested a bunch of brands of calcium chloride, and there were two different types, the higher of which would add something like 2 ppm of lithium over the course of a year (the value you now have).
https://www.advancedaquarist.com/2004/3/chemistry

What brand of calcium chloride are you using?

My conclusion in the old article:

Lithium does not seem to pose as much of a toxicity concern as many other ions, but in three of the samples (Dow, Warner, ESV) it is greatly elevated. Over a year, each of these would add about 2 ppm lithium, or 12 times the natural level. Is that too much? I am not sure. In a prior analysis of artificial salt mixes, Craig Bingman found that two salt mixes started out with greatly elevated lithium levels (90X over natural levels for Coralife and 6X for Seachem, with the others ranging from 1.5X - 3.1X). Typical aquaria surveyed by Ron Shimek contained about 0.6 ppm of lithium (3X over natural seawater) with a range from 0.015 ppm (0.08X) - 7 ppm (39 X).

It is well known that excess lithium has significant adverse effects of the development of sea urchin embryos,1,2 and many studies have been carried out in this area. The amount of lithium used in those studies, however, is typically around 500-3,000 ppm. It has also been shown that 345 ppm of lithium will result in death of the isopod limnoria.3

So while 2 ppm lithium delivered by these samples is greatly increased over the natural levels of 0.18 ppm, it is still small compared to the hundreds of ppm required to show toxic effects. Given that gap, and the fact that the lithium levels will likely be attenuated by water changes, I conclude that the lithium in these calcium chloride samples is not an excessive risk. Nevertheless, that is something that each aquarist can decide for themselves.

 

[Randy Holmes-Farley]

Coralife salt mix used to have very high lithium (far higher than yours, more than 12,000 ug/L, shown by Craig Bingman in 2000, see link below) and some folks blamed starfish problems on it, although I don't know if that was true or not.

http://web.archive.org/web/20001215...om/fish2/aqfm/1999/mar/features/1/default.asp

I doubt if any grade of magnesium chloride or sulfate has a specific lithium specification, but better grades may well have less.

I would not assume the lithium test by ICP will be perfect in a mag sulfate or chloride solution due to possible interferences that may not be there in seawater, but it is reasonable to try to test each at about 35 ppt and see what the lithium would be. We can evaluate the answer based on the lithium to magnesium ratio. This dissolve 35 grams in a liter or so. Exact concentration really doesn't matter, so, for example, half of what you add by weight will be water if you are using a hydrate, but that's fine (maybe better).

 

[salty joe]

I do have pumps with magnets in the tank. I'll check them out.
I haven't used a lot of calcium chloride but what I used was de-icer for driveways.
It sounds like maybe the lithium level in my tank isn't such a big deal-something killed those Trochus snails. A conch I got at the same time is doing better but not moving around as much as I'd expect.

FWIW, I use Cuprisorb, Puregen and carbon.