What all do you have in your tank? If it is a FOWLR
, you could do Hyposalinity in the DT.
Copper or hypo are the only two cures. Leaving the DT fallow when using a QT allows the Ich to die off due to not having a host.
You can try making sure water parameters are pristine and diet is optimal (garlic and vitamin supplements added) and see if the fish can overcome the Ich. The only problem is that many fish won't and even if they do, you still have Ich in the tank that can get future additions.