Note to self: if the output tube coming from the Kalk stirrer sits IN the water, the calcium buildup will eventually plug the tube and backup. The output tube carrying the saturated Kalk should have what they call an "air gap", meaning it should not touch the water in the sump. It needs to drop out of the tube just like doser outputs.
One more note self.....shaking the hose to see why the Kalk was backed up was also a bad idea. (5' of backed up Kalk came out of the 3/4" tube, once the calcium plug came out). I should have thought that through a little better......