try mixing and adding your Kalkwasser like this: pour 15ml of 5% Acetic Acid (or ordinary Distilled White Vinegar from the grocery store -- same thing) into a 1 liter (1 quart) container. Dissolve 1/2 teaspoon of lab-grade Ca(OH)2 (or commercial Kalkwasser mix) in the Acetic Acid, and then dilute to 1 liter (1 quart) volume with either RO/DI water, or even tank water.
15 ml is more Vinegar than some people are comfortable with, but I use it constantly with no problems. There should be no sediment in the mixture, or just a little bit at most. You can let the sediment settle out if you don't like the white flakes in your tank. I just drip the liquid and the sediment both into my tank.