actually by drilling the cylinder itself at the bottom, above the box, to input the beckett driven water, will definitely minimise the problem....u will lose one or 2 inch of reaction height since u start higher now...but i think for a tall skimmer like yours...the benefits outweigh the loss of the 2 inch reaction height
and the box will have water with much less microbubbles to return to the sump....
something like the position below...and then do the swirling angle just like what u have now...should reduce alot of microbubbles at the box below...