gnatp2 how many shrooms did you kalk at once?
I got a pepperment shrimp a while ago that ate the center of a bunch of shrooms over night and I lost two tangs because of it. I am sure that if a lot of shrooms are killed at once it will have some serious effect on your water quality. Whether it's toxin or not I don't know. But I do lean to it being toxin.
I still kill mushrooms with kalk. I just kill them a little at a time.