Stainless filter screens

[Pescador]

You might also try inline filters for bilge pumps on boats, they are cheap and have clear plastic covers. you will still might have to swap out the stainless screen for plastic. Maybe CdnTire?

Here's one for an example
http://www.boaterbits.ca/review/prod...0/category/90/

Maybe a filter bag on your overflow line in the sump would help as well.