I have searched the internet looking for a hard answer but can't find one. I am doing a salt treatment of 1 tbsp per 2 gals in my 75 gel tank that had ich. I am going on my 4th week at this dose and would like to do 1 more week before I start backing down. How long can most fish tolerate this level of salt before they start to be harmed by it? I don't want to go too long and kill fish. Thanks.