Phang
If you intend to dose your tank, you can follow Tanzy instruction but prepare to change more than 50% of the water. You also need a super efficent skimmer. Guess you also have to run plenty of carbon too.
Best is to do dipping, less stress to the corals.
Anyway all this has to be carried out in 2 phase. The 2nd time is about 2 wks later, that is when you'll find flatworm again. Guess these are hatched from eggs in the LR.