zero, zilch, none, I haven't yet found a reason to add salt to a freshwater tank outside of specified short term treatment of certain diseases. Plants from what I understand do not like salt long term, and Freshwater fish are definately better off without it.
dave
That is a good, eye opening article. I have been using aquarium salt, not table, and keep the levels really low (right around 1 ppm) and the fish seem ok. I think that I will not add the salt with the next water change and slowly get the salt out. Sorry that this is getting off topic. Thanks for the advice.
The Salt Myth has many Facets, and unfortunately many ill informed supporters. Salt has it's purpose as a medications for specific issues as mentioned by a few folks here.
As far as nitrites, The chloride ion will help block the harmful effects of nitrite. It does not have to be salt that provides the Chloride, but Salt is an easy thing to add for this purpose. Nitrites of course should only be an issue in an uncycled tank (temporary and avoidable) or if we make bonehead mistake (temporary we hope) But Salt will definately help in those cases.
Dave