I'm sort of skeptical too... about "reef-safe" ich medications. It seems most of them do not state the ingredients on the lebel even, which scares me a lot.
However, in one occasion I did try "ICH*ATTACK" by Kordon, in my 57 gallon reef setup.
This, since I "really" didn't want to disassemble my established reef rocks and some inexpensive but happy soft corals to chase after the fish for a QT. I thought I'd give it a go since fish seemed happier in the reef than in a bare tank with all his mates in close proximity and without much hiding places.
I keep 3 common tangs, purple tang, powder brown Japanese tang, and a hippo blue tang...the 3 victims of ich this time. The two sand gobies and the single clownfish seemed to be somewhat more immune.
The result was mixed...
Ich was gone and never came back in the last several months and all fish and inverts did survive, including cleaner shrimps that often do not make it through any form of chemical madness.
What I can't prove though, is if the fish was tough enough to shake them on their own with some garlic dosed foods, or if the "Kordon ICH ATTACK" additive actually had an effect on the eradication.
I'm assuming the combination of both and I never really thought or researched about it much after this incident.
I believe the same with all the experts here though, since I am no doctor or paid scientist; that best way to fight "ich" in a more immediate and permanent solution is, of course, copper or other 100% proven ways. This is if one needs to be POSITIVE that it's gone. (of course, in a Quarantine Tank!)
In my case, it was more a battle and a decision, to figure out...if the very crowded QT tank for long duration was healthier than leaving them in a normally therapeutic reef and seeing if they can shake it on their own with some help from me (with addition of reef-safe chemical meds and garlic laced foods)... I chose the latter, and this time I was lucky (I am assuming).
But I can't say if I will recommend this, or if I can even repeat the same results... Reef Tanks can rock on or whither away for a million reasons, and for me, I won...just this time, that's my view.
The odds it seems, from the results of lots of others...is probably as good as Vegas blackjack game though, for "reef-safe" medications (additives). It seems somewhat relatively safe, but effectiveness...I can't say yes or no.