One after thought...there are some flowers or plants that attract white flies. Grow a few of these plants in pots not in the GB's but in the same area. They will move the flies to those plants where you can now treat them by misting with soap water without contaminating your AP system. My ex-girlfriend (The Garden Lady) planted them in my Organic Garden, not sure what they are called but they look like bright yellows daisies.

Got these sites from "The Garden Lady"

http://www.ext.colostate.edu/pubs/insect/05587.html Mentions all the plants whiteflies are attracted to and what to do. Also mentions chemicals and wasps that kill the whitefly.

http://www.ghorganics.com/whiteflies.html Mentions nicotiana or flowering tobacco. This site names flowers and other devices.

Just remember to adapt this formation to your system...not all can be used with AP