Only suggested to test for total hardness as calcium carbonate during this purification processing step. It is important to ensure consistency in sample output/ data at the beginning and end of the week during a three-week period. Performing this test daily would not necessarily provide any added value since other sampling points at further purification stages will capture the quality output.Risk control: The sampling activities and frequency shall be done per test instruction within the PQ phase in addition to the routine sampling (e.g., sample randomization in order to ensure that the sample output remains consistently within specifications during routine monitoring over and above).