Ok that is your problem. The Hannah checker kits are inaccurate(except the Hanna phosphate checker). The alkalinity meter reads too low. The calcium checker is super sensitive. Rodi water often times is not pure enough to perform the test( even with zero TDS). To get best results on calcium checker you would have to use an insulin syringe for measurements, and get some lab grade water to increase accuracy. If not it will always read your calcium very high.
I wanted to like them but, but too many trucks were necessary to get accurate results. I now went back to using salifert test kit, and Red Sea foundation is pretty good also. Get your water tested with another test kit before you perform any corrections.