Using a simple submersible pump. This model is 10000L per hour capacity.
Dropped through the neck of the IBC and left for a period does a fantastic job.
Another possibility is a 4″ well pump that will drop straight through.
The best all around way is to have a pump connected to IBC with a recirc loop and tap back to top of iBC
and a T for decanting product when ready. This way the IBC can be left in place while being emptied.
Here it s in action…..