Well, the sponge and underwater route doesn't work for me. They would still let the bubbles pass and be inside the sump.
Maybe I'm doing something wrong.
My drain pulls a lot of air, which in turn makes a lot of micro bubbles that explode when they surface.
The micro bubble burst is what creates the mist.
Right now, I have a filter sock that keeps all the bubble explosion to the inside of the sock and I have very minimal to not even noticeable mist.
I use a drawstring type to close the top side of the sock.
The umbrella idea looks better, but without the sock, I'd have to cover the entire compartment, which also houses the skimmer and would make it almost impossible to contain all the area with the skimmer in the way.
The only solution I could find was to use a recirculating skimmer and use the drain to feed the skimmer.
Drawback of that is the return would have to be dialed down considerably, right?