Kalk is generally used to MAINTAIN ALK and Calcium while giving you a PH boost. Not generally to be used to boost PH a significant amount because it can blow your ALK and Calcium sky high. Kalk will only effect those 3 parameters.
2 part/ 4 part/ all the others are generally set to target individual nutrients and raise them and eventually maintain. This can also be used to stretch water changes if done correctly if nitrate and phosphates are in line.
I dose Kalk currently in a very mild mix 1/2 tsp per gallon. This is enough to keep my tank happy and stable, dosed over a 24hr period in 24 intervals to . I have a nicely stock mixed reef with most lps and softies.
Water changes are still necessary.
This is my understanding and how i have come to use it.