Kalk is cheap and very easy to do. Just can be a little messy at times. Seems like every time I top off my reactor I spill some Kalk powder. Wet paper towel and wipe everything down and good to go. Bought a 5 gallon bucket of Kalk about 2 years ago from BRS. Still have plenty left and tanks going strong.
Reactor or stirrer, Dosing pump, & Kalk
Reservoir to mix Kalk in, Dosing pump, & Kalk
And whatever method you choose to control the dose. I'd steer clear of having it feed from you ATO. Have had serious issues in the past from overdosing because of this.
I don't see myself not dosing Kalk for any reason. Cheap, PH boost, Easy!