Well I for one have been battling Ich for a 2 months now. I have spent a good portion of my life reading on the internet and speaking with people who have been around in the salt water industry for a long time. There is not 1 way to kill or fight ich, there are many ways to kill/fight ich. I have tried almost everyway to kill/fight ich in a reef tank. Lowering the SP WILL get rid of SW ich, if you drop your SG to 1.018 or lower they simply can not re-produce.(this means make babies ) If you want my honest opinion on ich. It is like herpies, once you get it, you always have it. If you stress a fish in anyway and you have ich in your tank it will show up. Keeping your water healthy and avoiding temp swings while you acclimate your fish is the easist way of keeping ich out of your tank. If you can not seem to get rid of it. I would only advise a product called "The Fish Keeper" They have a Marine/Reef Formula that from my experience it by far the best stuff out there. Look it up and try it if you really cant not seem to get it out of a tank.