I've used it in
FOWLR tank when I first took over maintaining it and it was a mess... now the tank is a pretty sweet reef

Have not used it with sensitive inverts or corals - anything like that makes me skittish.
Follow instructions to the letter - do a 20 % water change post-treatment, turn off ozone if you use it, and dose it early in the day as it can drop the amount of dissolved oxygen in the water - and that normally drops at night anyway.
I have not heard of anyone having adverse reactions using it, but I've not known anyone to use it in an "advanced" reef tank.
I concur that the source of the problem has to be indentified and fixed, or you'll have to keep dosing the stuff periodically. I think it can be a good way to get ahead of the stuff if you just can't do it any other way, but until the underlying problem is identified and corrected, the problem will just keep coming back.
HTH
Jenn
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LFS Owner:
Imagine Ocean

Just keep skimming, just keep skimming, just keep skimming, skimming skimming! What do we do? We skim, skim, skim!