I'm thinking maybe pack it full of media and throw a powerhead at the bottom and take off the collection cap and let it overflow back into the sump? I have some spare rio 600's. Just and FYI, the part of the sump it sits in is full of water almost all the way up the skimmer.
yeah, that would basically turn it into an in-sump canister filter.
Personally, depending on how the sump is configured, I would use it to hold a 200 micron filter bag and have the drain from the tank dump into that, as long as it could drain out the bottom.