Hi Dave, I can't think of anything that would survive a good soaking/scrubbing in bleach. This would be a reliable and cheap method. Best, John John T Lonsdale PhD 407 Edgewood Drive, Exton, Pennsylvania 19341, USA Home: 610 594 9232 Cell: 484 678 9856 Fax: 315 571 9232 Visit "Edgewood" - The Lonsdale Garden at http://www.edgewoodgardens.net/ USDA Zone 6b