I ran a simple batch experiment with only an initial inoculation, 500 rpm stirring, and temperature control at 30 °C—no pumps, dilutions, or automatic OD zeroing. Everything looked fine until around 6–10 hours, when the normalized OD abruptly dropped from about 4 × back to 2 × and the implied growth rate dove to –0.3…–0.4 h⁻¹ in a single collapse, then stayed flat for the remainder of the run. I haven’t configured any dosing or cleaning cycles that could explain this, and there are no corresponding pump or air‐bleed events in the log. Has anyone seen a one-time, large OD crash like this in a pure batch/stir+temperature run? Could it be caused by bubbles, probe fouling, hidden auto-calibration, or something else? Any pointers on additional diagnostics or workarounds would be much appreciated!
THANKS!
Thomas