As long as you split up the kalk additions throughout the day and night, that won't be an issue. I would also add that if you are aerating the tank with a skimmer and powerheads, the pH won't get too high.
KalKwasser needs to be added based on alkalinity test results. My favorite hobby alkalinity kit that I've used is Salifert, but there are others. I would only trust some kind of titration kit for alk, over digital ones or meters.
A doser is better than through an auto top off, or through a reactor, since a doser will be constant instead of changing with evaporation.
I like that you are performing water changes. People seem to be doing less and less of those lately.
