Is it bad if some of the undissolved Kalkwasser gets into my system regularly? What's the big deal? Won't it dissolve anyway? I dose kalk into my return pump chamber in my sump anyway so it shoots right through the pump and gets mixed up quick.
It can be bad. Solid kalk can act as a seed for crystalization of calcium ions out of solution, at least until it gets some gunk on it. In other words, adding unmixed kalk can lower your calcium and alkalinity. You should really seek to minimize what gets into the tank.
