1, Put the pump on top of the ibc and draw around the base of the pump with a marker pen. Allow a bit of extra space for the jubilee clip that secures the transfer hose to the outflow of the transfer pump.
2, Drill a hole on the marker pen line large enough to get the blade of a jig saw into the hole.
3, Use a jig saw to cut along the marker pen line.
4, remove the cut out piece of plastic.
5, Plop the transfer pump through the hole.
Thats what I did so I know what I mean