I have used seacure copper. Only because that was what was available at the time that I needed it. It worked perfect for me. I know everyone here loves hypo, but from what I have heard copper is the only SURE CURE. Just make sure that you check your copper levels at least daily. Too much=dead fish. Not enough= extended time in quarantine.
like i said, FISH ONLY TANK !!! of course its harmful, its supposed to be !! thats why you only do it if you have to, and hopefully you know what your doing when you do it, i even put the amount to use .......
you can get a product called garlic gaurd that comes in liquid form to soak you food in prior to feeding. The are a variety of different garlic products out there to chose from. Garlic is used to boost the immune system but there is a bit of discussion on whether it really deters ich. Garlic is safe with inverts. I only really use Garlic to promote eating if I see a fish not eating. I use a minute amount and mix it with some tank water and let the food sit for a while prior to feeding. Mostly I soak food in Zoe(marine Viatamins).