Total Hardness – Water Based Mud Testing


The total hardness test gives an indication of the level of soluble Calcium and Magnesium ions present in the mud.

Such ions are considered detrimental since, under conditions of high pH (>11.5), they may render polymer, treatments for viscosity and fluid loss less effective.

High levels of hardness will also flocculate Bentonite.

The total hardness should be controlled below 400 mg/L and must not be allowed to rise above 600 mg/L.


Total Hardness is usually expressed in mg/l CaCo3.

Sources of Error

Can be difficult to see the end point of the test.

Total hardness is reported as mg/L CaCO3. Multiply this value by 2.5 to get the required value.

Magnesium hardness can be calculated by subtracting the Calcium hardness value from the total hardness. This is common practice but ignores the fact that Magnesium has a higher atomic weight than Calcium. However, errors are small.


#1 maqbool a. soomro 2015-12-18 16:13
have any thumb rule to determine the pm/pf/pf.please reply