If you do research you will find the following:
1) Hypo-salinity works but isn't at all convenient (six+ weeks and you have to remove ALL your fish from the tank and treat separately) and still stresses the fish
2) Copper works but isn't reef-safe either and similarly, stresses the fish
Neither of these are options for you if you can't get a big enough hospital tank.
Everything else doesn't have very much data supporting anything either way.
3) Products
Since most products don't release what they contain and often don't explain how they achieve their purported benefits, most people tend to lack faith in them. However, many products have a wide variety of testimonials from people who believe the product removed ich from the tank.
Many products claim to "kill" ich by improving the immune response system of the fish. Many people believe certain chemicals cause the fish to improve the function of their normal skin/membrane protection which in turn, prevents ich from being able to attach to the fish thus killing the life-cycle. Whether or not they work, you're likely to hear many different thoughts on it as ich is a tricky little beast and so are reefkeepers.
It is easy to think ich is gone from your tank because you no longer see spots anymore. That doesn't necessarily mean the ich is gone (nor even that the ich is not successfully attacking your fish); it could simply mean the ich is being held in check due to your tank conditions. If you add another fish, you may see another outbreak.
4) Predatory help
Cleaner shrimp, wrasses...do not eat Ich. I wouldn't go as far as some people that conclude this means they do not help fish fight ich, but most research I have found suggests that cleaner shrimp are not going to rid your tank of ich nor are they even likely to help.
5) Garlic, home remedies
Many people believe Garlic has natural healing abilities. I'm not going to support or dispute that... However, it is widely believed that garlic is one substance which can indeed cause fish to produce an excessive coating/membrane, which many people believe could help fight ich. Garlic is used in some products that claim to kill ich. Pepper-based products are also common based on this same theory.
The problem is that nobody has done any formal testing on whether or not these products work and if they do, when/under what circumstances to they work/fail to work.
I've heard an awful lot of reports from people using products that "worked". I believe many of these reports are simply cases where the ich is still in the tank but now held at bay by healthier fish who finally developed enough resistance and strength. I also believe there are enough reports to make it unlikely that this is the case for every report. So, I think some of these products can and do work, at least in certain situations.
6) UV
UV only impacts the organisms in the water that passes under the lamp. Ich is pretty tough too, so you have to ensure the flow is slow enough to kill the beast. But it does kill it. It has not proven effective to eliminate ich from the tank since there is no way you are going to get all your ich to pass under the lamp. However, it has been shown to be able to keep ich from being transferred from one tank to another (if you have ich in one tank, put the output from that tank through a UV, and then into a second tank...the 2nd tank won't have ich). But that isn't of much benefit in most cases.
It is possible that UV could help reduce ich to a level that the fish's natural defenses could become more effective; however, that hasn't been demonstrated sufficiently either.
Ich is an obligate parasite. It cannot complete its lifecycle without a fish host. It has a known life-cycle, which is why the hypo-salinity treatment must be done for such a long period of time. You can think ich is not in your tank because you don't see it anymore but it very well may be... Your tank CAN be ich free...permanently. There are many who don't believe that, but it is 100% true. If you want to be absolutely certain the ich is gone from you tank, I'd recommend hyposalinity treatment although I know you say you can't due to size constraints (me too).
I have a few susceptible tangs in my tank and I have ich. They've pretty much always had ich, although usually I either can't see it or only see a spot or two and usually only on my Powder Blue and Hippo. I've had 3 "outbreaks", all of them after introducing a new fish, none of which were horrible, but one was bad enough that I was enormously concerned with the well-being of some of my fish.
I have quite a large system and had no way to treat the fish out of the tank so I went out and purchased about a half-ton of kick-ich and a mammoth UV system. I was in panic mode, what can I say. I had already tried garlic and other techniques which appeared to possibly help in the two previous outbreaks but didn't seem to be having as much of an effect this time around.
The end of the story is that I chickend out on the Kick Ich treatment and the fish battled through it before I even had a chance to set up the UV. No losses, at least not from ich (I've had two suicides over the past two years but that's about it).
Fish can and do develop resistance to ich, but ich is an ever-changing beast and resistence is just that...it isn't immunity.
What to do...what to do. I guess that is a question for each of us. Since I haven't been planning on adding any new fish to my system and I just moved and have a dedicated fish room and all, I was considering going through the hypo-salinity route for all my fish...imagine it -- a perfectly ich-less system! But we'll see. It is still going to be quite an undertaking for me to perform that kind of quarantine system.
I'd love to hear what you end up deciding to do and how it works out. I'd love to give the kick-ich I bought a whirl and have it work for me...but I'm still super-nervous about adding chemicals like that to my tank. It is very comforting to hear some local refers have used it ok though.
Anyway, I guess I'm done rambling.
