When you qualify your BactoBox® setup, always use an SBT dilution vial (bundled as DV01).
For the regular (weekly) QC test, use the dilution vial that you intend to use going forward for your own measurements. This depends on your use case and may be either of:
When you change your BactoBox® setup.
Example: You replace the flow cell.
Example: You replace the external filter.
Example: You replace the tubing kit.
When you switch from the SBT dilution vial to the DIY dilution vial.