It appears that CO2 recovered is calculated backwards.
The proper way to do it is:
Beginning + Total Recovered + CO2 purchases = Ending + Brewing Usage + Pkg Usage + Eng’g Losses
Normally. We know the actual CO2 recovered and the CO2 usage for Brw and Pkg is by meter. Therefore, The Eng’g losses is a calculated figure (because we have no meter for the losses).
And now, for the accuracy of the meters, especially if consumption was actually controlled, in the absence of calibration, we can estimate correction factor for Brw and/or Pkg meter and the correction is absorbed in the Engineering Losses.
By the way, how much did we vent this month as I understand we still had problems early this month?