Hi BikBok. I have a API ph test kit 3 months old nutrafin/Hagen ph test kit 3 weeks old and tested the water in my cichlid tank with both kits and found the Nutrafin read a lot lower.
API 7.6
Nutrafin 6.5
On the same day I took some of the water up to the LFS and it was 7.6.
Would be interested to know if anyone else is able to do a similar test.