How to account for ullage/waste left in tank

Probably a simple one but couldn’t find the way to do it correctly.
I’ve racked one tank but there is X L that I cannot use. i/e. below the racking arm.
How do I properly account for that and mark the tank as empty and ready to be used?

Hi Mike,

Any remnant of liquid in a tank can be removed in Production > Actions > Empty Vessel. This will close down the batch and allow you to transfer a different beer into the vessel. As this is recorded as wastage, it will not form part of any payable duty.