I have been using only kalk for the past two years and I have always had problems keeping my alk in the correct range due to the fact that my corals were using it up as they build thier skeletons. After reading the link on this two part solution I realized they are used in conjunction with each other I started using the two part solution and with in 5 days I have hit a target of where my tank should be ,I am still adding kalk with my top off water but I am now watching my levels alot closer and adjusting the amount of two part solution to keep with in the levels I want.

Barry