The good thinkg about peppermint shrimps is that they can get aptasia in location where it would be impossible to kill with kalk. If you are lucky and get the one that eats aptasia, they do a pretty good job of keeping them under control.
If I remember correctly, there are two common type of peppermint shrimps that are available in this hobby. One of them will eat aptasia, and the other one does not. I have peppermint shrimps from several LFS, and none of them would touch aptasia. However - I have had really good luck with peppermint shrimps that I have purchased from Twins (located in Stockton).
The only problem with peppermint shrimps are that they tend to disappear. I don't know what it is about them, but they tend to disappear pretty fast. I put two into my nano tank, and never saw them again. I must have put at least 10 in my 120G, and I usually see only one or two in the evening. When I don't see any for a few weeks, then I go out and buy more.