Just a couple of Quick notes:
Don't be suprised at the rumors, mis-information and confusion. The reason the article was written is that there is more incorrect information than correct information out there. If you really want to get deep into ich studies and accurate information, research the fish farm industry. People who make a living keeping fish alive pay for good scientific research and are far less prone to mythology. Bottom line is results are what matter in buisiness, so myths get people fired, and accurate information gets people paid.
Aside from my own experiences and the experiences of other I did a lot of reading before I wrote the article. I am not an expert on osmoregulation, but I do know that salt interferes with ich ability to take in and release fluids (Osmoregulation as I understand it) This effect keep necessary electrolytes from being replaced and essentially dehydrates (for lack of a better term) the ich. I am sure this process can be explained more clearly by one of our resident biologists.
Suffice it to say that salt will kill ich regardless of temperature. Since ich is not vulnerable when on the fish (this is the same for meds as well) we increase temps to get the ich off the fish faster. If we do not increase temps then we simply have to treat for longer periods, and more importantly our fish have ich on them for longer. IME Ich causes far more stress to fish than salt or high temps so I elevate the temp to get the ich off the fish.
At temperatures above 86*F ich cannot survive. So if we can get temps that high without harming fish, and ensure that all of the tank is at or above that temp, ich will die off without any other treatment. I personally am not comfortable with raising temps quite that high and leaving them there. Many folks do it and are successful, I worry about cold spots (And my tanks are more evenly heated than most) and I worry about the stress that high temps cause many fish. So I rely on Salt and use heat to help the cause as much as I can. IME Heat causes more stress than salt, and the real key is to apply the treatment and maintain it 100% until ich is dead. you let the tank cool for even a few minutes the chance of a new outbreak exists.
Anyone who claims that salt won't kill ich has not done their research. I challenge them to show me one piece of scientific evidence where Freshwater ich has survived NaCL at 5 ppt or above. I have only found one study that shows ich surviving as much as 5 ppt. Most strains of freshwater ich die even at very low dosages, and the exceptions will always die at 5 ppt which equates to roughly 2.5 teaspoons of table salt per gallon of water.
I always say research the subject as much as you can. I can tell you there is a lot of information and study data on ich. There are also great articles citing good studies, and plenty of articles with no research or good information behind them. I have done the research and am very confident in the information I put to paper. I have cured ich with salt at temperature ranging from 74* up to 82*. I do not take my fish above 82* in most cases because I don't like to do so. I have heard from enough people and read enough information about ich to know that 86* is the limit for ich, but do not trust it as a treatment alone because it is too difficult to maintain temperature perfectly in a fish tank.
Dave
