I don't know that there is a limit on the maximum tdcg limit that would necessitate degassing as you propose. As you know the tdcg is an indicator of what is going on in your transformer. If the gasses are stable it is probable more an indication of what has gone on in the transformer in the...
When the motor is first started you have zero flow, the flow from the pump will be dependent on speed, as the motor begins accelerating the pump, the flow will increase. Look at your pump curve and your motor starting torque curves, and you will see that the bhp requirement of the pump is...