Quarterly maintenance, and one deep clean a year.
The industry here sells a single annual visit. An AC system in Dubai runs eight to ten months a year, and biofilm doesn't wait for your anniversary.
Two products, two different jobs
What actually protects you, in order
- Moisture control The condition that permits growth. Nothing else on this list matters while this is unresolved.
- Substrate removal The organic film that feeds it. This is the work, and it's mechanical.
- Suppression Slowing what comes back between visits. Useful, recurring, and third.
Tea tree is third on that list, and it is not a treatment for mould.
In a 2015 University of Adelaide study, tea tree oil outperformed vinegar, ethanol and two hospital-grade disinfectants against two common indoor fungi. It was tested on agar over seven days — and the same paper found the effect declining by day 14, with sporulation resuming.
That isn't a flaw in the product. It's the reason a suppression product only makes sense on a recurring cycle, and the reason we come back every quarter rather than once a year. Killing a fungus is not the same as removing it, and neither is the same as fixing the water that fed it.
Rogawansamy S, Gaskin S, Taylor M, Pisaniello D. An Evaluation of Antifungal Agents for the Treatment of Fungal Contamination in Indoor Air Environments. Int J Environ Res Public Health. 2015;12(6):6319–6332. doi:10.3390/ijerph120606319