I recently started working on Drillbench as a part of my dissertation work. I wanted to know why my pit gain steadily rises even after the BOP is closed and PUMP is shut off.. Also please correct me if im wrong in my procedure of kick simulation

1. Simulation stops when kick is detected(choke is initially closed)
2. BOP is closed
3.Simulation proceeds and stops again and asks to turn off Pump
4. Pump is turned off
5. Simulation progresses a little and stops
6. I open the choke.
Now to circulate the kick out, i reckon i must turn on the Pump with Step 6.
What should be the circulation value of the pump then ??
I also want to know how the from the simulation we can interpret the "circulation of the kick out through the chokeline" procedure.
Thanks