Originally Posted by sepulatian
I completely agree. You can do what you want, but I ask you to take a look in the common treatments FAQ at the top of disease and treatment. There are only two methods that are proven to kill ich. They are copper and hypo. There is also a list of other meds that people have tried. They are all posts from members here. We do not make this stuff up as we go along. Quick cure or any other "miracle cure" will not kill ich. Do yourself and your fish a favor and just hypo them.
I disagree slightly. Quick cure is not as sketchy as other medications that have no known active ingredient on the "miracle cure" scale. On the contrary, the effects of malachite green and formalin are very well known and they are used as tried and true treatments for many things.
However, the possible risks (and they are significant) to both fish, inverts and humans - make it a far less desirable treatment choice, IMO, than hypo and copper.
You would not want to use formalin on fish with any chance or indication of open wounds. Both malachite green and formalin are pretty significant risks to humans if mishandled.
So when you compare overall treatment success, availability to hobbyists and safety concerns...hypo and copper (and hypo specifically) are much better bets, IMO.