[SAT]

To be clear, the trick is to prevent the cysts (tomonts) which have fallen off the fish from hatching and then reinfecting the fish. This can be done several different ways. Hyposalinity can prevent the cysts from hatching... providing the salinity is low enough and you don't have a tolerant strain. Copper will kill the parasites (tomites) when they hatch. CP presumably does the same without subjecting the fish to heavy metal poisoning. TTM moves the fish away from the tomonts before they can hatch.

You cannot tell visually whether all the parasites have fallen off the fish and it is normal for the fish to look better quite a while before all the parasites are off. They can remain on the fish for as long as 12 days, so that's the minimum treatment time. That minimum presumes you immediately remove the fish from that environment after treatment is concluded, so the cysts remaining in the tank cannot reinfect. The tank remains contaminated until either you sterilize it or 2-3 months have past.