I'm not sure exactly what happened, but you might have caused a precipitation event if you used enough Kalk. I'd test the alkalinity once the water is clear, or take a small sample, and let it settle. Once you have an alkalinity number, we can work from there. Probably, there's nothing hugely wrong and I'm being excessively cautious, though. Up to you.
There are other ways to kill polyps. You might be able to inject them with vinegar, for example. I'd leave that until we're sure the tank is okay.