quarantine tank ???

[pirate]

So once my quarantined fish leave the Q tank do I need to change the water? So far all the fish are healthy and looking good. Do I change the water if I used meds? When do you guys change the water in the Q tank?
How long do you leave the fish in quarantine? This is the first time I've used a quarantine tank, but I'm planning on doing it to all the fish and corals befor I put it into my tank.
Thanks