That's the problem with wrong dosage. In simple words, Ca & Kh has to be belanced. If you add KH plus too much and too fast, your Ca will drop and Vice Versa!
Thus if you intend to dose any form of Ca or Kh+, you have to ensure that you dose slowly according to the instructions on the labels and not dose when you feel like it. Wrong dosage will also cuz ionic imbalance and this could be detrimental to your tank - heard of tank crash.
I suggest you reading and fully understand how to best to maintain Ca & Kh before you cause anymore unnecessary stress to your inhabitants.
If you need, get some senior to personally help you.