Regarding your query about biofilms and Wondro, the following reference indicates that the thymol component of oil of thyme may have inhibitory effects on biofilm formation:
Braga PC et al. "Thymol inhibits Candida albicans biofilm formation and mature biofilm", Intl Journal of Antimicrobial Agents, Volume 31, Issue 5, Pp. 472-477, May 2008. http://www.ncbi.nlm.nih.gov/pubmed/18329858
The original formulation of Wondro included 48 fl oz of oil of thyme for each 25 gallon batch, something that was added to ameliorate the odor. However, it appears that this may have amplified its efficacy by adding an antifungal component in addition to its acetaldehyde scavenging potential.
This is an exploration of the biochemical aspects of the herbal remedy Wondro in relation to the disease-causing potential of acetaldehyde released by the commensal yeast Candida Albicans.