If you follow the directions in this article and drip it in just as you would regular kalkwasser you won't have problems with low ph.
http://www.reefscapes.net/articles/b...alkwasser.html

When you combine kalkwasser with vinegar you are making calcium acetate. The acetate becomes a carbon source for bacteria. So it can be similar to dosing vodka in that you may see a reduction in N & P but you can also end up with too little nutrients for your corals. This is what happened to me when I was using it. I saw a noticable reduction in algae growth which was good but after a while my softies were not at all happy and I had to back off on the vinegar.