Sorry to derail this discussion even further:Viktor Jarikov wrote:When treating ich with salt, it usually takes at least a week at about 2 (or 1-3) teaspoons (5 gram each; or ~3 US lbs per 100 US gal) per US gallon and when the visible parasites disappear, another week is recommended on top. Non-iodized salt is needed. Better without anti-caking agents (calcium salts, chalk that murky up water).
Iodide enriched salt is 100% safe with fish.
This thread on a Swedish forum discusses Iodine and Anti-caking:
http://www.zoopet.com/forum/showthread. ... ost1559060
Here's a (rough) translation:
(And hey, Viktor, I thought you worked in chemistry and would know the difference ;) )Azur translated wrote: The use of iodized salt in aquaria is an old wife's tale, and almost impossible to exterminate.
It relies on the confusion between the element Iodine (highly toxic, at room temperature it is purple crystals) and its ion, Iodide (harmless, added to salt in many countries where the local soil is low in iodine - lack of iodide in the diet causes thyroid problems). The cause for this confusion is probably at least in part caused by salt packaging has "Added Iodine" on the label, where it would be correct to say "Added Iodide".
It would be similar to saying that Chlorine (toxic and corrosive gas) and its ion Chloride (essential compound and one half of the content in table-salt)
In summary, it doesn't matter if the salt has iodide or not in it - if anything, it may actually do some GOOD to have iodide in the salt.
No matter how many times we try to kill this myth, it crops back up again
There is a long post two down on ferrycyanide [confusion probably stems from the fact that it's got "cyanide" in its name, which under some circumstances is extremely toxic], which is the most harmful of the ones used as anti-caking agents. I'm just going to go over the summary:
Tabel Salt contains approximately 8 ppm ferrocyanide dry weight. If you add 50g salt to a 100 liter tank, the salt content is 0.5 ppt (0.05%). Lethal dose (LD50) of ferrocyanide is 19 ppm for fish. The amount of ferrocyanide is 0.5 * 0.000008ppt = 4 parts per billion, or roughly a fifth of one thousandth of the lethal dose.
Ferrocyanide does convert to cyanide when exposed to UV light, but unless you mistakenly put UV tubes instead of regular fluorescent tubes in your aquarium, this shouldn't be a problem either. Ferrocyanide also gets broken down to harmless compounds by the beneficial bacteria in the filter.
[I'm not sure, but I think Viktor's suggested salt dose is about 2ppt, or 2g per liter, which is higher than the above example of 50g/100liter (0.5g / liter), but only by four times, and it doesn't substantially alter the numbers above].
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Mats