Agreed, copper and hypo (and emptying the tank) are the only ways to remove ich. But for treating ich, I have a different opinion.
I'm of the opinion that it's always going to be hard and a crapshoot to keep a tank ich-free... one mistake with timing or QT and the whole tank has ich again.
But when i say "the whole tank has ich again", i mean that the ich organism is simply in the tank, in the water column, not that the fish are succumbing to the parasite.
I'm sure I'll get all sort of contradictions on this, there should be Ich Police designation, but this only my opinion.
I prefer to keep the fish healthy and if any breakouts occur, I feed crushed raw garlic in with my food, daily, and within 4-5 days the fish are not showing any symptoms again and are fine.
I use no UV sterilizer in my tank, only use garlic, and have not had a breakout for over 2 years, now, i believe. used to happen sometimes when adding new fish, espeically the first couple of years, when my tank wasn't fully established nor balanced.
my idea is that trying to keep ich out is more futile than treating the occasional outbreak. ich is almost a non-issue with my system, as we always have and use fresh garlic in the house.
i use 2 raw cloves of crushed garlic in my 170 gallon system, once a day for 4-5 days, and then every other day, if I ever see something. has always worked. You can smell the garlic in the tank the day after dosing, but that seems to be the only side-effect.
just my opinion, and simply sharing my experience. Not telling anyone what to do.