I found a new way to kill Aptasia.

[Orm Embar]

I've tried kalkwasser via syringe; I could never get the boiling water to work (between the time to load the syringe and get it to the tank, it seems to cool off darn quickly) . . . I'll have to remember this trick

 

[Joe's Coral Reef]

Berghia Nudibranchs. Fun and fully effective. Just try to find a new home for them once you are done with them as without aiptasia, they die.

These work, but the aiptasia will usually always return. The Berghia just can't eat every one before they eventually die off.