I've used Ich attack - meh.
For 150 gallons, that !@#$ gets expensive in a hurry. It makes your tank smell like crap and I'm not sure it does anything more than just feeding them does.
An interesting bit of info re: Copper - as bad as that crap is, you'll find trace of it in a lot of 'essential elements' style water additives. It's more common than we think.
Oh, and in a QT, never EVER use prime, stress coat or any of that stuff. Chelated copper can essentially be 'transformed' into a super-toxic form of copper through those de-chorinators and ammonia reducers. You essentially spin offer copper ions and you end up with some nasty stuff.
If you're going to run a QT, you just need to be prepared to do a daily small water change in it to reduce ammonia levels. You can't built up nitrifying bacteria in it because you don't want the media in there for the ich to take refuge in. Some people will keep a sponge in their sump to build up the bacteria, then introduce it to the QT when they put a fish in there, but I think I'd prefer go bare-bottom with it. You also don't want to use prime because of its impact on the copper medications.
QTs are a bit of a pain in the ass.
It's my own fault for expecting the Titanic to beat the iceberg this year.