Sounds to me like you don't/didn't quarantine. Like Justin said this is a must in the reef building hobby. For example, that coral beauty that you just got. If you had put it in a quarantine tank (I'm assuming you didn't) for 2 or 4 weeks, you would have had to (more than likely) still deal with the ich problem. But here is where the beauty of a quarantine comes in. You can treat that fish with medicines and other methods (i.e. Hypo-salinity and copper) you can't do in your main DT. Not to mention there is no way that the Ich could spread to your other fish (being in a different tank and all).
Now I know how hard it is when you just start to get to that point where you get FISH. Yes I can get fish now! Then some jerk like myself comes and tells you that you can't put your fish in your main tank for 2-4 weeks. WHAT?!?! Trust me getting into a good quarantine habit could help you avoid loosing the thousands of dollars you have invested in your Reef tank (or will come to invest
). Ich is a tough cookie to crack once it gets into your system it is a pain in the you know what. Like Justing said it can live undetected and sometimes dormant until parameters are perfect the BAM ich on all your fish. So practice good quarantine habits and you can avoid these kinds of messes.
But now that we have that out of the way. Here is an article located on Wet Web Media on ich and battling it
IchArt2Mar