Hypo salinity never hurt any of my fish in QT. It's safe, and there is also speculation that it is beneficial because they don't have to work as hard regulating their body fluids because it is closer to what their natural body fluid is. Hypo does well with a few common diseases and parasites. Do it for 6 weeks and you will find that if it goes through the treatment without any signs of anything else. It's a good bet that you are safe. Barring that your display system is parasite free. Nothing is ever 100% but I can tell you that the opposite is 100% if you use the dump and pray method, I would say at one point in your hobby it will be 100% sure there will be something nasty in your tank. So, I would rather have the odds work in my favor. I am sure there are other preventatives out there, this one to me, seems to be the cheapest and most effective.