A couple of things to note.
IMO You should never add any additive that you can not test for, it btings in too many unknowns and you could possible add WAY more than you ever need in the first place.
That being said I dont dose anything. I got my ph/alk/ and calcium where I want them and I drip Kalk to maintain those levels. Occasionally I add some magnisium, but it is far and few between, and could probally be eliminated if I did more water changes.
For Kalk info look for a thread title "Ok all you Kalk users" by Thomas for a alot of good info.