When I dip I always dipped for ten minutes. I have been told by a very experienced person (Joel) that if they die from the freshwater dip they were not going to make it anyway. And yes when I dipped I dipped everynight until the problem was gone. It only took 2 nights in a row, and the problem was gone. Remember to put a bubbler in the FW dip tank, as the water should be well oxygenated. Hope this helps, and good luck.