new QT water or Re-use?

[Gregs]

well not quite. because you still need to rinse the tank out and give it a good scrub, even then cysts and other parasites could survive a simple rinse. so i let the tanks dry out then fill with hot water/balance with cold water. then let it sit in fresh water for a few days before i mix salt.
so its quite a process compared to... just doing a super copper treatment instead for example? that is probably just as effective or even more...