Are the results of the Total Hardness Test Kit Model 5-B valid if the sample turns pink or red after adding UniVer reagent and then blue after one drop of titrant?
Total Hardness Test Kit Model 5-B turning red or purple.
If the Hardness test kit turns a red or purple color initially, but changes to blue after the addition of the titrant, this indicates that the sample is very close to the endpoint. The results can be expressed as less than one grain per gallon. Analyzing a known concentration value of hardness can confirm test performance.