I use Coral Rx & Lugol's for dips...and I still got Montipora Eating Nudibranchs and AEFW in my QT (this was a while back). That's why I dip, use a QT, and have a grow-out tank...all before corals go into my main display. You can't expect to have 100% success with just a dip. Eggs hatch, critters can hide, etc.