Which Calcium to should I Believe?

[RobertP]

I have Red sea pro calcium test kit and it is telling me that that my tank is between 400 and 420. However, I have trouble telling the difference between purple and blue so not 100% sure it is correct.
So I bought a Hanna checker and it is saying my calcium is 580!!! I thought I screwed up the process so i did it again....4 times total and even got 590 once.
Now I am pretty new to marine and tank is only 5 months old and I am NOT dosing. My salt is Red Sea coral pro and at 1.025 and I am using rodi water.
At this point I really do not see how the hanna is correct because Im doing weekly 10-20% water changes. Also saw a lot of bad reviews on the hanna calcium checker. Mine is consistent...just consistently high.
What do you think?
thanks

 

[BYU]

hanna is horrible
i never got accurate readings so i called them they will tell u to buy a calibration kit and spend more money
I don't trust hanna
just my 2 cents

 

[ahiggins]

Ive never used hanna but i have used red sea and I know that salifert is a more accurate test than red sea.
That being said....your red sea is probably more accurate than hanna.