How can two Calcium Tests have such different results?

[sawdavis]

I have been struggling since last August to get my calcium levels up over 380 ppm. I used an API test kit. No matter how much Calcium I added, it remained stuck at 380 ppm. Then four days ago, I used a Salifert test kit I recently purchased and my Calcium level according to that kit was 460 PPM! I repeated the test to make sure I was doing it correctly and got the same result. How can these two kits have such different results? Which one should I believe?

 

[Copingwithpods]

Salifert, api is junk, it settles out, varies widely even when being careful. I'd trust the salifert for sure.

 

[JimWelsh]

+1 Salifert.

 

[sawdavis]

Thanks for responding!

 

[Duffer]

yep salifert is the one you go with...