I would not use chems to eradicate Ich...Personaly, i would of gone down teh hypo route...The Chem your using should tell you how long the process takes....however, with hypo, its about 6 weeks..
http://www.monsterfishkeepers.com/forums/showthread.php?t=133645
http://www.monsterfishkeepers.com/forums/showthread.php?t=133645