I just read up on it and it looks like you can't use it to add kalkwasser. The way I read it when the ph becomes more then the set point the power is turned on to your dosing device. This works for co2. If you want to dose Kalkwasser you need to turn the power on when the pH is below the set point.
I went with the American Marine Pinpoint, it will allow you to control both the co2 and kalkwasser. I would look for that option because you will likely want to do both in the future.