Quarantine for new fish: After a few newbie hard lessons in the beginning, I set up a QT for new fish. Initially, this tank was connected as a refugium to my sump, and then disconnected when in use as a QT. I use the hyposalinity routine, and have had great success with acclimating new fish including some more finicky Butterfly fish such as Copperbands and Pearlscales. The entire QT process usually takes 2 or 3 months for me. Here is a good article on the benefits of hypo.
http://www.advancedaquarist.com/2007/6/fish
I have always had a permanent QT with a canister filter, and I now keep some live rock in there as well. It is still multi purpose, and I QT some corals in there too. And I use it as an overflow frag tank, when I run out of room in my DT frag rack. I use water from my DT water changes, so no salt costs.
Pretty simple set-up actually. But the key is permanent. Most failures happen because of new set-ups (no stable nitrogen cycle), and the misuse of copper or other chemicals. I have had 100% success rate, when I used hypo. You can also use Prazipro at the beginning before you lower the salinity if you suspect internal parasites. Then after a few days, start the RODI water changes to lower the salinity to 1.009. And to raise, just use the DT tank water from water changes.