Do you have your fish in a QT/HT, or are you trying to treat in the Display? What kind of fish do you have and what else do you have in the display? Did you quarantine your fish? I'm assuming not, but it's a moot point now either way.
Not sure what ichx is, but can virtually guarantee you that it won't kill the ich. The only treatments known to kill ich are copper, tank transfer, chloroquine and hyposalinity. None of those can safely be done in a DT (possibly chloroquine and hypo if you have a fish only tank with no inverts.)
Other treatments, additives and immune boosters will not kill the ich and will at best suppress it to sub-clinical levels so it can flare again the next time a fish gets stressed.
Read though the stickies at the top of the forum on ich and treatments.
Prime shouldn't be necessary if you're in the DT. If you're in a HT that wasn't cycled, you almost certainly will have problems with NH4 and prime can be helpful. Do not combine it with copper treatments like cupramine, however.