Need your help

[htfn]

Hi, when I came back to home from my work tonight, I noticed my powder Blue has got lots of ich on his body. I tried to rescue powder blue from main tank for more than 4 hours but never success. I have invert. and mixed corals, so I can't use a copper. Do you think Hikari Ich-X Saltwater Treatment is work? It seem to me OK but I never got these problem before. What is quickest and best way to treat it before it gets too late. Powder Blue is my little girl's fish, so I can't loose it.
Please help