Test Kits - Help!

Thats a great point, thanks. Luna

 

Hopefully I can help later on tonight.
I just did my 2-week water change last night.
I know from all my past test (including the test last night) that my Ca is always ~ 360ppm right after a water change, using the API test kit.
I brought up the Alk from 9 to ~12 dkH last night.
I added some Ca, waited an hour, then added some Mag.

When I get home, I'll take dkH, Ca, and Mag readings, and bring levels up as required.
If I'm testing at 1400 Mag, and I still can't get the Ca up over 360ppm by adding more Ca, then I'm also going to assume something is fishy about the API Ca test.

 

Ok, well tested paramters when I got home.
Mag 1400 ppm
Ca 340 ppm
Alk 12 dkH

So I added a few more tablespoons of Ca.
Tested 2 hours later, and Ca was up to 440 ppm.
I guess we know now that the API test is sensitive to changes in Ca levels (as it had better be). Now the fun part is going to be buying different brand Ca test kits to find out how much of a variance there is. 60 ppm seems like too much to be mismeasured, because it's 3 drops of a difference in Ca #2 reagent in the API kit.