Bring about 10 pieces of burlap and replace when they are jammed up with crud (you can scrape off some non obnoxious stuff like coffee)
Put a capfull of bleach in the filtered water and just take it home with you. Putting it in a standard evap pond could make a stink.
Link below has more info:
http://goo.gl/QU3VI
Here are some pics from the link:
