[Jaws]

Well it looks like my fish were infected with velvet after I added some live rock from another hobbyist's tank. I managed to catch all the fish from the display tank, quarantine them, and treat them. My question is, if I fill the display tank back up with just freshwater for a week or so, will that kill whatever parasites were in there? The tank was fish only with recently cycled live rock so I realize that's all dead rock again, which is fine, but I want to make sure no parasites survive as well.