If there is any solid material in the kalk (you mention a possible slurry situation), there's no easy way to know how much it is adding, but it can be a lot more than saturated kalk.
9.5 gallons of saturated kalk added to 550 gallons will add about 2 dKH of alkalinity.
If the reactor off allows a drop of 1.5 dKH, then the total addition (ignoring the extra from the slurry solids) is about 3.5 dKH.
Also bear in mind that demand is both pH and alk dependent, so if those change during a test, the values will also change.