How extensive is the problem? Does it look like this?
I realize that it seems horrible but the issue developed over several months, maybe even a year, so patience and wisdom would indicate the resolution should be well thought out and diligently applied. It may seem like it, but believe me, it's not an emergency.
Have Peppermint Shrimp been introduced
Have the large, most seriously offending Aiptasia been shot with vinegar, Kalk paste or other Aiptasia killing substance
May we see a pic of the tank to help you determine the best course of action
Aloha,
Mark