<a href=showthread.php?s=&postid=10737467#post10737467 target=_blank>Originally posted</a> by fingerwrinkles
Ken, from personal and professional experience my recommendation would be to take your fish out of your reef (I know, a major pain!!!) and put them in the quarantine tank.
Since your quarantine tank should be bare except perhaps for a couple PVC pipes, you do not need to "cycle" the tank before using it. Assuming you could catch your fish (nighttime is an excellent time to do this), you can drain out some of the water from your main tank to initially fill the quaratine tank (mixed with cured tap water to the desired salinity) and then med appropriately with copper. Once you catch the fish, give them a FW dip for a couple minutes (based upon the reaction of the fish) and then place them in the QT. Each morning look at the bottom of the QT tank to see if you see any spores that have dropped off your fish (they look like sugar on the bottom glass). You'll need to siphon these out in the AM. Also watch the fish and if you see a recurrent set of spots on the fish you'll need to repeat the FW dip process. Partial QT water changes can be made with fresh SW every day or two depending upon water quality deterioration. A sponge filter can be used to help with aeration / filtration of the QT. I'd also encourage the use of garlic based foods if your fish will take them.
Unfortunately, some texts advise a fish-free period of 6-8 weeks for the main tank to cycle out the parasites. I've personally done a 10 week fish-free period and 3-4 week quarantine period for all new fish to clean up an infected tank. Additionally, all new items - rocks, corals, snails, shrimp - are either dipped or QT themselves before going into the main tank.
This of course is the far end of the scale when it comes to protection, but anyone who's been around for some time can remember the painful lesson of giving into temptation and taking a chance with a new fish because the risk seemed OK at the time. It only takes one bout with ich and a loss or two to make one cautious (perhaps overly so) in the future.
As Rich and Jim note above, some tangs are ich magnets and there really aren't any valid corners to cut without raising the risk exposure significantly. I'd try to get your fish into a QT setup, clean them up while letting your tank re-set, and then start again. It'll be a bit of a hassle, but at least you will know that you are "clean".