KH test kit readings

[Sicklid]

When I test with my API KH kit lately, it does not turn BRIGHT yellow from blue like it used to... It turns pale yellow after the second drop is added. Anyone think that indicates 2 degrees hardness? Additional drops don't make it any brighter yellow. It is confounding me as I distinctly remember it going from blue to a very bright yellow with the single drop that caused the change. This has all happened since adding DIY co2.

 

[Devilishturtles]

Are you capping the test tube and shaking after each time? I assume you are, just checking. I don't have a clue about how CO2 affects your kH reading, but if additional drops are not changing the color at all, it sounds like your reading is 2 degrees.