I have been using the
tunze calcium dispenser for sometime now, it works on the same principal as you are talking about. I would not recomend doing it because it just does not stir the kalk enough, it does help a little though, and giving it a shake once a day is not convient for me. The problem is the flow through the chamber is not enough to keep the water inside saturated with kalk. I would just go with a actual kalk stirer or reactor. IMO
PS: I will have my dispenser for sale soon if your interested in trying it.