What brand of test kits are people out there using ? I have two kits (Hagen
and Aquarium Pharmaceuticals) for KH hardness, and they are giving me
different results. One says my water is about 60 PPM carbonate hardness, and
the other says about 90. These differing results are consistently
repeatable. Is there a brand out there that I can really trust?

I want a pretty precise result for the KH hardness so I can determine the
C02 levels on my water with a reasonable degree of accuracy.

Thank you for any help.