Yep. Love it a little less but still love it. The key for the Ca checker is getting really really clean water. RODI isn't clean enough from what people have said. I have a buddy that hooked me up with lab grade pure h2o that I use.
Hannah checkers are shiiiii.... I have phosphate and Alk and love them!! I had the calcium but didn't like it die to inconsistent result due to not have pure water.
In order of ease of use would be.
Alk
Phosphate
Calcium