for my overflow i used a piece of very course hard filterfloss.. it came in one of my pumps but since once the water gets to my pumps its been filtered like 2020320723075 times i didnt see the point...
i also used one of those bloodworm feeder ring baskets as a screener on my syphon line in one of my tanks.. however i used a dremel to open up the slits a bit more..