If anything I would question the eXact iDip... that thing is all over the place for me. I have multiple test kits of most of the parameters I test for... Nyos, Red Sea, Hanna Checker and the iDip. The iDip is by far the most inconsistent... sometimes unusable.
Well I just got my Aquaforest DKH test kit today and I'm gonna compare them to see the difference.



