Yep, what rr said
. I regularly use the vinegar through a syringe in my 10g. I have injected several large aiptasia amongst corals with no ill effects..save for some Xenia momentarily closing up. I use this simply because I don't have/use kalkwasser.
I've had mixed effects with boiling water. When they didn't die, they seemed to go on a reproducing frenzy. I had at one point easily 50-75 in my nano. I also had an explosion in my 30g. This could very well be coincidence but i just wanted to throw it out there.