Prazipro has a high oxygen demand from the bacteria that breaks down the glycol solvent that is used. If you have a skimmer you can run it without collecting anything in the cup during treatment. Adding an airstone to the tank is also a good idea. Your corals will likely react negatively, but if they are in good shape, they will handle it ok.
That commonly happens when a fish with a severe fluke infestation is given a FW dip - all of the flukes drop off at once, leaving the holes they made in the fish's skin wide open and the fish bleeds out. The only way around that is something that I've tried in the past - give the fish a short dip, try to just knock off a few flukes, and then 2 days later, repeat the process, and then again a third time. In reality, it is almost impossible to time this to knock off just the right number of flukes....
