Being colorblind, the calcium test kit that comes with the TFT-100 is impossible to use. I noticed that Taylor has the K-1567 kit that goes from red to blue which is easy to use. The only potential caveat is that it's measuring calcium hardness as CaCO3. Is it a simple matter of converting the results from the K-1567 to pure calcium by multiplying by 0.4? Or is the TFT kit also measuring calcium hardness?