Aside from what dDon says, if you dilute the water, you dilute the treatment. Do the change before the treatment, and youneed to remove any carbon.
There was a member that posted the composition of the Ick Kick. It does have some sort of antibiotic in it, and it boasts it gets rid of the swimming stage, but not the other stages.
I used it, and it did indeed clear things up, but then I did the 72 day fallow period. I would have to say, the ick Kick did seem to help nurse the fish back to health somewhat, after the 15 days, I cycled them into QT tanks with copper and a week with no copper before the display tank, and that seemed to work just fine. After all fish were out, i waited 72 days so I could salvage the rock and invertebrates.
The product literature boasts about whacking the swimming stage, which it may do just fine, it is the other stages that cause the problems as when the cysts burst the problem just keeps compounding each cycle till its all gone. UV will do the same thing.